Review of Critical Care Medicine

  • Blog Stats

    • 663,789 hits
  • Disclaimer

    The author does not take over any guarantee for the topicality, the correctness, completeness or quality of the information, made available. Liability claims against the author, concerning damage of idealistic or of material kind, which was caused by the use or not use of the presented information and/or by the use of incorrect and incomplete information, are in principle impossible, so far as not a deliberate or roughly negligent fault can be proved on the part of the author. The documents and graphics on this Web site can be affected by technical inaccuracies or misprints, for which we don't assume any liability. Furthermore,quotation from a book or the incidental capturing of copyrighted material in a segment of a MCQ should be considered as "FAIR USE".It is only for nonprofit educational purposes.The display is a regular part of the systematic instructional activities of this non-profit educational website and is meant entirely as help to solve the ever-challenging MCQs.Due respect has been given to great medical authors and their names displayed prominently alongside quotations/pictures or paragraphs.
  • Member of The Internet Defense League

  • Follow Review of Critical Care Medicine on WordPress.com
  • October 2021
    M T W T F S S
     123
    45678910
    11121314151617
    18192021222324
    25262728293031
  • Recommended Books

  • Webchat

Posts Tagged ‘All india MD/MS entrance exams MCQs’

Gynaecology & Obstetrics Notes

Posted by Dr KAMAL DEEP on January 21, 2011

1. Feto maternal transfusion is demonstrated in the mother by: a) Coombs test b) Kleihauer count c) Electrophoretic methods, d) reticulocyte count

Fetal red cells in the maternal circulation can be identified by use of the acid elution principle first described by Kleihauer, Brown, and Betke, or any of several modifications. Fetal erythrocytes contain hemoglobin F, which is more resistant to acid elution than hemoglobin A. After exposure to acid, only fetal hemoglobin remains. Fetal red cells can then be identified by uptake of a special stain and quantified on a peripheral smear (Fig. 29–7). This test is very accurate unless the maternal red cells carry excess fetal hemoglobin as the result of a hemoglobinopathy.

During all pregnancies, very small volumes of blood cells escape from the fetal intravascular compartment across the placental barrier into the maternal intervillous space. This observation is important for several reasons. It is the cause of maternal red cell isoimmunization, as discussed in Isoimmunization.Choavaratana and colleagues (1997) performed serial Kleihauer–Betke tests in 2000 pregnant women and found that, although the incidence of fetal–maternal hemorrhage in each trimester was high, the volume transfused from fetus to mother was very small .

D-positive fetal red blood cells in D-negative maternal blood can be detected by the rosette test. Maternal red cells are mixed with anti-D antibodies, which coat any fetal (D-positive) cells present in the sample. Indicator red cells bearing the D-antigen are then added, and rosettes form around the fetal cells as the indicator cells attach to them by the antibodies. Rosettes indicate that fetal D-positive cells are present.

2.

clip_image002

Broad ligament
The broad ligament is a sheet-like fold of peritoneum, oriented in the coronal plane that runs from the lateral pelvic wall to the uterus, and encloses the uterine tube in its superior margin (Fig. 5.50). The part of the broad ligament between the origin of the mesovarium and the uterine tube is the mesosalpinx.
The peritoneum of the mesovarium becomes firmly attached to the ovary as the surface epithelium of the ovary. The ovaries are positioned with their long axis in the vertical plane. The ovarian vessels, nerves, and lymphatics enter the superior pole of the ovary from a lateral position and are covered by another raised fold of peritoneum, which with the structures it contains forms the suspensory ligament of ovary (infundibulopelvic ligament).
The inferior pole of the ovary is attached to a fibromuscular band of tissue (the ligament of ovary), which courses medially in the margin of the mesovarium to the uterus and then continues anterolaterally as the round ligament of uterus (Fig. 5.50). The round ligament of uterus passes over the pelvic inlet to reach the deep inguinal ring and then courses through the inguinal canal to end in connective tissue related to the labium majus in the perineum. Both the ligament of ovary and the round ligament of uterus are remnants of the gubernaculum, which attached the gonad to the labioscrotal swellings in the embryo.

3.

clip_image001[4]clip_image003[4]

clip_image005[4]

Between the perineal membrane and the membranous layer of superficial fascia is the superficial perineal pouch, and the principal structures in this pouch are the erectile tissues of the penis and clitoris and associated skeletal muscles

Structures in the superficial perineal pouch

The superficial perineal pouch contains:

  • erectile structures that join together to form the penis in men and the clitoris in women; and
  • skeletal muscles that are associated mainly with parts of the erectile structures attached to the the perineal membrane and adjacent bone

The superficial perineal pouch contains three pairs of muscles: the ischiocavernosus, bulbospongiosus, and superficial transverse perineal muscles

3.Lymph Nodes:-Lymphatic channels from superficial tissues of the penis  drain mainly into superficial inguinal nodes, as do lymphatic channels from the scrotum or labia majora.

The glans penis,clitoris, labia minora, and the terminal inferior end of the vagina drain into deep inguinal nodes

Lymphatics from the testes drain via channels that ascend in the spermatic cord, pass through the inguinal canal, and course up the posterior abdominal wall to connect directly with lateral aortic and preaortic nodesaround the aorta, at approximately vertebral levels L1 and L2.

Lymphatics from most pelvic viscera drain mainly into lymph nodes distributed along the internal iliac and external iliac arteries and their associated branches (Fig. 5.67), which drain into nodes associated with the common iliac arteries and then into nodes associated with the lateral surfaces of the abdominal aorta. In turn, these lateral aortic nodes drain into the lumbar trunks, which continue to the origin of the thoracic duct at approximately vertebral level T12.

Lymphatics of vulva transverse the labia from medial to lateral side. The lymphatic drainage of the labia proceeds to the upper vulva and mons, then to the inguinal and femoral nodes with both superficial and deep lymph nodes.

The last deep femoral node is called the Cloquet’s node; spread beyond this node affects the lymph nodes of the pelvis. The tumor may also invade adjacent organs such as the vagina, urethra, and rectumand spread via their lymphatic.

Vessels from the lower part of the uterine body pass mostly to the external iliac nodes, with those from the cervix. From the upper part of the body, the fundus and the uterine tubes, vessels accompany those of the ovaries to the lateral aortic and pre-aortic nodes. A few pass to the external iliac nodes. The region surrounding the isthmic part of the uterine tube is drained along the round ligament to the superficial inguinal nodes.

image

image

image

image

4.Pelvic Floor

The muscles that span the pelvic floor are collectively known as the pelvic diaphragm(Fig. 38-8). This diaphragm consists of the levator ani and coccygeus muscles along with their superior and inferior investing layers of fasciae. Inferior to the pelvic diaphragm, the perineal membrane and perineal body also contribute to the pelvic floor.

Perineal body —The perineal body is an ill-defined but important connective tissue structure into which muscles of the pelvic floor and the perineum attach. It is positioned in the midline along the posterior border of the perineal membrane, to which it attaches. The posterior end of the urogenital hiatus in the levator ani muscles is also connected to it.

The deep transverse perineal muscles intersect at the perineal body; in women, the sphincter urethrovaginalis also attaches to the perineal body. Other muscles that connect to the perineal body include the external anal sphincter, the superficial transverse perineal muscles and the bulbospongiosus muscles of the perineum.

Urogenital Diaphragm/Triangular Ligament:-The perineal membrane is related above to a thin space called the deep perineal pouch (deep perineal space) which contains a layer of skeletal muscle and various neurovascular elements. The deep perineal pouch is open above and is not separated from more superior structures by a distinct layer of fascia. The parts of perineal membrane and structures in the deep perineal pouch, enclosed by the urogenital hiatus above, therefore contribute to the pelvic floor and support elements of the urogenital system in the pelvic cavity, even though the perineal membrane and deep perineal pouch are usually considered parts of the perineum.

5.Benign ovarian teratomas are usually cystic structures that on histologic examination contain elements from all three germ cell layers. The word teratoma was first advanced by Virchow and translated literally means “monstrous growth.” Teratomas of the ovary may be benign or malignant. Although dermoid is a misnomer, it is the most common term used to describe the benign cystic tumor, composed of mature cells, whereas the malignant variety is composed of immature cells (immature teratoma). Dermoid is a descriptive term in that it emphasizes the preponderance of ectodermal tissue with some mesodermal and rare endodermal derivatives. Malignant teratomas that are immature are usually solid with some cystic areas and histologically contain immature or embryonic-appearing tissueBenign teratomas may undergo malignant transformation. This occurs in approximately 1% to 2% of dermoids, usually in women over age 40.

6.because of their relative prevalence, dermoids are the tumor most frequently reported in a series of women with adnexal torsion. However, the relative risk of adnexal torsion is higher with parovarian cysts, solid benign tumors, and serous cysts of the ovary. The right ovary has a greater tendency to twist (3 to 2) than does the left ovary. Torsion of a malignant ovarian tumor is comparatively rare.Adnexal torsion occurs most commonly during the reproductive years, with the average patient being in her mid-20s.Pregnancy appears to predispose women to adnexal torsion, with approximately one in five women being pregnant when the condition is diagnosed. Most susceptible are ovaries that are enlarged secondary to ovulation induction during early pregnancy.

7.Ovarian Abnormalities in pregnancy

The best treatment of an asymptomatic ovarian cyst in the first trimester
a) Immediate laparotomy b) Laporatomy in second trimester…ANS
c) Laparotomy after delivery d) Leave it alone till it becomes symptomatic

D-nothing should be left alone.They should be observed serially with imaging techniques, and resection is performed if they grow, begin to look suspicious, or become symptomatic

Any type of ovarian mass may complicate pregnancy

Management

Early in pregnancy, ovarian enlargement less than 6 cm in diameter usually is the consequence of corpus luteum formation. With the advent of high-resolution sonography, Thornton and Wells (1987) proposed a conservative approach to management based on ultrasonic characteristics. They recommend resection of all cysts suspected of rupture or torsion, those capable of obstructing labor, and measuring more than 10 cm in diameter because of the increased risk of cancer in large cysts. Cysts 5 cm or less could be left alone, and indeed, most undergo spontaneous resolution

Recommendations

It seems reasonable to remove all ovarian masses over 10 cm because of the substantive risk of malignancy. Tumors from 6 to 10 cm should be carefully evaluated for the possibility of neoplastic disease by ultrasound, MRI, or both. If evaluation suggests a neoplasm, then resection is indicated. If the corpus luteum is removed before 10 weeks, then 17-OH-progesterone, 250 mg intramuscularly, is given weekly until 10 weeks. Cystic masses that are thought to be benign or are less than 6 cm are observed serially with imaging techniques, and resection is performed if they grow, begin to look suspicious, or become symptomatic. In general, we have performed elective surgery at 16 to 20 weeks. Most masses that will regress will have done so by that time.

8.OCP—-Decreased risk of endometrial and ovarian cancer

INCREASES—liver, cervix, and breast cancer

Tamoxifen is an antagonist of the estrogen receptor in breast tissue via its active metabolite, hydroxytamoxifen. In other tissues such as the endometrium, it behaves as an agonist(increases endometrial ca risk but decreases breast cancer risk), hence tamoxifen may be characterized as a mixed agonist/antagonist.

OESTROGEN UNOPPOSED INCREASES RISK OF breast and endometrial cancer

9.Women with TOA most commonly present with lower abdominal pain and with unilateral or bilateral adnexal masses. Fever and leukocytosis may be absent. Abscess rupture causes severe pain with chills, fever, and progressive peritonitis. If large volumes of pus are released into the peritoneal cavity, infection may spread upward along the colonic gutters to form subphrenic abscesses that cause shoulder pain. Sonography is typically diagnostic.

25-year old married infertile woman having regular menstruation, fever. lower abdominal pain and dysmenorrhoea presents herself at the OPD. On examination, there are bilateral soft tender masses of 3″ diameter in both fornices and uterus is of normal size. The most likely diagnosis is,
a) Cystic ovaries b) Tubo-ovarian masses
c) Ectopic pregnancy d) Tuberculous salpingitis

10.The size of ovum is : a) 0.133 mm, b) 0.144 mm, c) 0.2 mm, d) None of the above

The mature ovum  measures 120-130 u/0.133 mm

11.The second maturation division of the human ovum occurs at the time of: a) fertilisation b) implantation c) ovulation d) puberty.

12.Relaxin

This protein hormone has structural features that are similar to insulin and insulin-like growth factors I and II. Its major biological action is remodeling of the connective tissue of the reproductive tract, thus allowing accommodation of pregnancy and successful parturition (Weiss and colleagues, 1993). Relaxin is secreted by the corpus luteum, decidua, and placenta in a pattern similar to that of chorionic gonadotropin (hCG). It is also secreted by the heart, and increased levels have been found in association with heart failure (Fisher and co-workers, 2002).

The role of relaxin during human pregnancy is not completely defined, however, it is known to have effects on the biochemical structure of the cervix (Bell and colleagues, 1993). The hormone also affects myometrial contractility, which may be implicated in preterm birth. Increases in peripheral joint laxity during human pregnancy do not correlate with serum relaxin levels (Marnach and co-workers, 2003; Schauberger and colleagues, 1996

13.Females with diabetes, hypertension or taking diet rich in fat are at higher risk. This is called Corpus cancer syndrome which consist of obesity, hypertension and diabetes.

Posted in Medical | Tagged: , , , , , , , , , , | 5 Comments »

Obstetrics

Posted by Dr KAMAL DEEP on January 20, 2011

1. Actions of CRH on the Fetal Adrenal Gland

As discussed in Chapter 3 (see Fetal Adrenal Glands), the human fetal adrenal glands are morphologically, functionally, and physiologically remarkable organs. At term, the fetal adrenal glands weigh the same as those in the adult and are similar in size to the adjacent fetal kidney. The daily production of steroids by the fetal adrenal glands near term is estimated to be 100 to 200 mg/day, which is higher than the 30 to 40 mg/day seen in adult adrenals at rest. Within the fetal adrenal gland, steroidogenic function and zonation are different from the adult. For example, significant amounts of cortisol are not produced in the fetal adrenal gland until the last trimester. As a result, fetal cortisol levels increase during the last weeks of gestation (Murphy, 1982). During this same period, levels of dehydroepiandrosterone sulfate (DHEA-S) production also are increasing significantly, leading to increases in maternal estrogens, particularly estriol. The increase in adrenal activity occurs in contrast to fetal adrenocorticotropic hormone (ACTH) levels which do not increase until the stress of actual labor.

This substantial growth and increased steroid synthesis during latter gestation is at a time when fetal plasma ACTH levels appear to decline (Winters and co-workers, 1974). Thus, many investigators have surmised that there must be growth and steroidogenesis stimuli for these glands in addition to ACTH. Two observations have made it extremely likely that factors secreted by the placenta play a key role in the regulation of steroidogenesis during late gestation. First, the fact that ACTH levels do not increase significantly during the last part of gestation makes it likely that growth and differentiation of the fetal adrenal glands are influenced by factors secreted by the placenta. Second, the fetal zone of the adrenal gland undergoes rapid involution immediately after birth when placenta-derived factors are no longer available. Many believe that CRH of placental origin is one of the critical components that facilitates fetal adrenal hypertrophy and increased steroidogenesis late in gestation. Indeed, in vitro studies have shown that CRH is able to stimulate fetal adrenal DHEA-S and cortisol biosynthesis (Parker and associates, 1999; Smith and co-workers, 1998). The ability of CRH to regulate the adrenal glands and of the adrenals to regulate placental production of CRH has led to the idea of a feed-forward endocrine cascade that occurs late in gestation (Fig. 6–19).

Placental CRH has been proposed to play several roles in the regulation of parturition. First, placental CRH may enhance fetal cortisol production, which would provide positive feedback on the placenta to produce more CRH. The resulting high level of CRH may modulate myometrial contractility. Second, cortisol has been proposed to affect the myometrium indirectly by stimulating the membranes to increase prostaglandin synthesis. Third, CRH has been shown to stimulate fetal adrenal C19-steroid synthesis, leading to increased substrate for placental aromatization. The resulting elevation in estrogens would shift the estrogen-to-progesterone ratio and promote the expression of a series of contractile proteins in the myometrium, leading to a loss of myometrial quiescence.

Ref:- Williams

2.Prolactin

Maternal plasma levels of prolactin increase markedly during the course of normal pregnancy. Serum concentration levels are usually 10-fold greater at term—about 150 ng/mL—compared with normal nonpregnant women. Paradoxically, after delivery, the plasma prolactin concentration decreases even in women who are breast feeding. During early lactation, pulsatile bursts of prolactin secretion occur apparently in response to suckling. The physiological cause of the marked increase in prolactin prior to parturition is not entirely certain. It is known, however, that estrogen stimulation increases the number of anterior pituitary lactotrophs and may stimulate the release of prolactin from these cells (Andersen, 1982). Thyroid-releasing hormone also acts to cause an increased prolactin level in pregnant compared with nonpregnant women, but the response decreases as pregnancy advances (Andersen, 1982; Miyamoto, 1984). Serotonin also is believed to increase prolactin, and prolactin-inhibiting factor (dopamine) inhibits its secretion.

The principal function of maternal serum prolactin is to ensure lactation. Early in pregnancy, prolactin acts to initiate DNA synthesis and mitosis of glandular epithelial cells and the presecretory alveolar cells of the breast. Prolactin also increases the number of estrogen and prolactin receptors in these same cells. Finally, prolactin promotes mammary alveolar cell RNA synthesis, galactopoiesis, and production of casein and lactalbumin, lactose, and lipids (Andersen, 1982). Kauppila and co-workers (1987) found that a woman with an isolated prolactin deficiency failed to lactate after two pregnancies, establishing the absolute necessity of prolactin for lactation but not for successful pregnancy outcome.

Prolactin is present in amnionic fluid in high concentrations. Levels of up to 10,000 ng/mL are found at 20 to 26 weeks, thereafter, levels decrease and reach a nadir after 34 weeks. Several investigators have presented convincing evidence that the uterine decidua is the site of prolactin synthesis in amnionic fluid (see Chap. 3, Decidual Prolactin Production). Although the exact function of amnionic fluid prolactin is not known, it has been suggested that amnionic fluid prolactin impairs the transfer of water from the fetus into the maternal compartment, thus preventing fetal dehydration during late pregnancy when amnionic fluid is normally hypotonic.

 

3.Fetal Heart Rate Patterns   ;-It is now generally accepted that interpretation of fetal heart rate patterns can be problematic because of the lack of agreement on definitions and nomenclature (Freeman, 2002). The National Institute of Child Health and Human Development Research Planning Workshop (1997) brought together investigators with expertise in the field to propose standardized, unambiguous definitions for interpretation of fetal heart rate patterns during labor. The definitions proposed as a result of this workshop will be used in this chapter. It is important to recognize that interpretation of electronic fetal heart rate data is based on the visual pattern of the heart rate as portrayed on chart recorder graph paper. Thus, the choice of vertical and horizontal scaling greatly affects the appearance of the fetal heart rate. Scaling factors recommended by the workshop are 30 beats per minute (beats/min or bpm) per vertical cm (range, 30 to 240 beats/min) and 3 cm/min chart recorder paper speed. Fetal heart rate variation is falsely displayed at the slower 1 cm/min paper speed when compared with that of the smoother baseline recorded at 3 cm/min (Fig. 18–6). Thus, pattern recognition can be considerably distorted depending on the scaling factors used.

 

Fetal heart rate obtained by scalp electrode and recorded at 1 cm/min compared with that of 3 cm/min chart recorder paper speed.

Baseline Fetal Heart Activity

Baseline fetal heart activity refers to the modal characteristics that prevail apart from periodic accelerations or decelerations associated with uterine contractions. Descriptive characteristics of baseline fetal heart activity include rate, beat-to-beat variability, fetal arrhythmia, and distinct patterns such as sinusoidal or saltatory fetal heart rates.

Rate

With increasing fetal maturation, the heart rate decreases. This continues postnatally such that the average rate is 90 beats/min by age 8 (Behrman, 1992). Pillai and James (1990) longitudinally studied fetal heart rate characteristics in 43 normal pregnancies. The baseline fetal heart rate decreased an average of 24 beats/min between 16 weeks and term, or approximately 1 beat/min per week. It is postulated that this normal gradual slowing of the fetal heart rate corresponds to maturation of parasympathetic (vagal) heart control (Renou and co-workers, 1969).

The baseline fetal heart rate is the approximate mean rate rounded to increments of 5 beats/min during a 10-minute tracing segment. In any 10-minute window, the minimum interpretable baseline duration must be at least 2 minutes. If the baseline fetal heart rate is less than 110 beats/min, it is termed bradycardia; if the baseline rate is greater than 160 beats/min, it is termed tachycardia. The average fetal heart rate is considered to be the result of tonic balance between accelerator and decelerator influences on pacemaker cells. In this concept, the sympathetic system is the accelerator influence, and the parasympathetic system is the decelerator factor mediated via vagal slowing of heart rate (Dawes, 1985). Heart rate also is under the control of arterial chemoreceptors such that both hypoxia and hypercapnia can modulate rate. More severe and prolonged hypoxia, with a rising blood lactate level and severe metabolic acidemia, induces a prolonged fall of heart rate due to direct effects on the myocardium.

Bradycardia

During the third trimester, the normal mean baseline fetal heart rate has generally been accepted to be between 120 and 160 beats/min. The lower normal limit is disputed internationally with some investigators recommending 110 beats/min (Manassiev, 1996). Pragmatically, a rate between 100 and 119 beats/min, in the absence of other changes, usually is not considered to represent fetal compromise. Such low but potentially normal baseline heart rates also have been attributed to head compression from occiput posterior or transverse positions, particularly during second-stage labor (Young and Weinstein, 1976). Such mild bradycardias were observed in 2 percent of monitored pregnancies and averaged about 50 minutes in duration. Freeman and colleagues (2003) have concluded that bradycardia within the range of 80 to 120 beats/min with good variability is reassuring. Interpretation of rates less than 80 beats/min is problematic, and such rates generally are considered nonreassuring.

Some causes of fetal bradycardia include congenital heart block and serious fetal compromise. Figure 18–7 shows bradycardia in a fetus dying from placental abruption. Maternal hypothermia under general anesthesia for repair of a cerebral aneurysm or during maternal cardiopulmonary bypass for open-heart surgery also can cause fetal bradycardia (see Chap. 44, Valve Replacement During Pregnancy). Sustained fetal bradycardia in the setting of severe pyelonephritis and maternal hypothermia also has been reported (Hankins and co-workers, 1997). These infants apparently are not harmed by several hours of such bradycardia.

Fetal bradycardia measured with a scalp electrode in a pregnancy complicated by placental abruption and subsequent fetal death.

Tachycardia

Fetal tachycardia is defined as a baseline heart rate in excess of 160 beats/min. The most common explanation for fetal tachycardia is maternal fever from amnionitis, although fever from any source can increase baseline fetal heart rate. Such infections also have been observed to induce fetal tachycardia before overt maternal fever is diagnosed (Gilstrap and associates, 1987). Fetal tachycardia caused by maternal infection typically is not associated with fetal compromise unless there are associated periodic heart rate changes or fetal sepsis.

Other causes of fetal tachycardia include fetal compromise, cardiac arrhythmias, and maternal administration of parasympathetic (atropine) or sympathomimetic (terbutaline) drugs. The key feature to distinguish fetal compromise in association with tachycardia seems to be concomitant heart rate decelerations. Prompt relief of the compromising event, such as correction of maternal hypotension caused by epidural analgesia, can result in fetal recovery.

Wandering Baseline

This baseline rate is unsteady and “wanders” between 120 and 160 beats/min (Freeman and colleagues, 2003). This rare finding is suggestive of a neurologically abnormal fetus and may occur as a preterminal event.

Beat-to-Beat Variability

Baseline variability is an important index of cardiovascular function and appears to be regulated largely by the autonomic nervous system (Kozuma and colleagues, 1997). That is, sympathetic and parasympathetic “push-pull,” mediated via the sinoatrial node, produces moment-to-moment or beat-to-beat oscillation of the baseline heart rate. Such irregularity of the heart rate is defined as baseline variability. Variability is further divided into short term and long term.

Short-term variability reflects the instantaneous change in fetal heart rate from one beat—or R wave—to the next. This variability is a measure of the time interval between cardiac systoles (Fig. 18–8). Short-term variability can most reliably be determined to be normally present only when electrocardiac cycles are measured directly with a scalp electrode. Long-term variability is used to describe the oscillatory changes that occur during the course of 1 minute and result in the waviness of the baseline (Fig. 18–9). The normal frequency of such waves is three to five cycles per minute (Freeman and co-authors, 2003).

It should be recognized that precise quantitative analysis of both short- and long-term variability presents a number of frustrating problems due to technical and scaling factors. For example, Parer and co-workers (1985) evaluated 22 mathematical formulas designed to quantify heart rate variability and most were unsatisfactory. Consequently, most clinical interpretation is based on visual analysis with subjective judgment of the smoothness or flatness of the baseline. According to Freeman and colleagues (2003), there is no current evidence that the distinction between short- and long-term variability has any clinical relevance. Similarly, the NICHD Workshop (1997) did not recommend differentiating short- and long-term variability because in actual practice they are visually determined as a unit. The workshop panel defined baseline variability as those baseline fluctuations of two cycles per minute or greater. They recommended the criteria shown in Figure 18–10 for quantification of variability. Normal beat-to-beat variability was accepted to be 6 to 25 beats/min.

jpg

 

Grades of baseline fetal heart rate variability (irregular fluctuations in the baseline of 2 cycles per minute or greater) together with a sinusoidal pattern. The sinusoidal pattern differs from variability in that it has a smooth, sinelike pattern of regular fluctuation and is excluded in the definition of fetal heart rate variability. (1) Undetectable, absent variability; (2) minimal  5 beats/min variability; (3) moderate (normal), 6 to 25 beats/min variability; (4) marked, > 25 beats/min variability; (5) sinusoidal pattern. (From National Institute of Child Health and Human Development Research Planning Workshop, 1997.)

Several physiological and pathological processes can affect or interfere with beat-to-beat variability. Dawes and co-workers (1981) described increased variability during fetal breathing. In healthy infants, short-term variability is attributable to respiratory sinus arrhythmia (Divon and co-workers, 1986). Fetal body movements also affect variability (Van Geijn and co-workers, 1980). Pillai and James (1990) reported increased baseline variability with advancing gestation. Up to 30 weeks, baseline characteristics were similar during both fetal rest and activity. After 30 weeks, fetal inactivity was associated with diminished baseline variability and conversely, variability was increased during fetal activity. Fetal gender does not affect heart rate variability (Ogueh and Steer, 1998).

It is important to recognize that the baseline fetal heart rate becomes more physiologically fixed (less variable) as the rate increases. Conversely, there is more instability or variability of the baseline at lower heart rates. This phenomenon presumably reflects less cardiovascular physiological wandering as beat-to-beat intervals shorten due to increasing heart rate.

Diminished beat-to-beat variability can be an ominous sign indicating a seriously compromised fetus. Paul and co-workers (1975) reported that loss of variability in combination with decelerations was associated with fetal acidemia. They analyzed variability in the 20 minutes preceding delivery in 194 pregnancies. Decreased variability was defined as 5 or fewer beats/min excursion of the baseline (see Fig. 18–10), whereas acceptable variability exceeded this range. Fetal scalp pH was measured 1119 times in these pregnancies, and mean values were found to be increasingly more acidemic when decreased variability was added to progressively intense heart rate decelerations. For example, mean fetal scalp pH of about 7.10 was found when severe decelerations were combined with 5 beats/min or less variability compared with a pH about 7.20 when greater variability was associated with similarly severe decelerations.

Severe maternal acidemia also can cause decreased fetal beat-to-beat variability, as shown in Figure 18–11 in a mother with diabetic ketoacidosis. The precise pathological mechanisms by which fetal hypoxemia results in diminished beat-to-beat variability are not totally understood.

Interestingly, mild degrees of fetal hypoxemia have been reported actually to increase variability, at least at the outset of the hypoxic episode (Murotsuki and co-authors, 1997). According to Dawes (1985), it seems probable that the loss of variability is a result of metabolic acidemia that causes depression of the fetal brainstem or the heart itself. Thus, diminished beat-to-beat variability, when a reflection of compromised fetal condition, likely reflects acidemia rather than hypoxia.

A common cause of diminished beat-to-beat variability is analgesic drugs given during labor (see Chap. 19, Parenteral Agents). A large variety of central nervous system depressant drugs can cause transient diminished beat-to-beat variability. Included are narcotics, barbiturates, phenothiazines, tranquilizers, and general anesthetics. Diminished variability occurs regularly within 5 to 10 minutes following intravenous meperidine administration, and the effects may last up to 60 minutes or longer depending on the dosage given (Petrie, 1993). Butorphanol given intravenously diminishes fetal heart rate reactivity (Schucker and colleagues, 1996). Hill and colleagues (2003), in a study performed at Parkland Hospital, found that 5 beats/min or less variability occurred in 30 percent of women given continuous intravenous meperidine compared with 7 percent in those given continuous labor epidural analgesia using 0.0625-percent bupivacaine and 2 g/mL of fentanyl.

Magnesium sulfate, widely used in the United States for tocolysis as well as management of hypertensive women, has been arguably associated with diminished beat-to-beat variability. Hallak and colleagues (1999) randomly assigned 34 normal, nonlaboring women to standard magnesium sulfate infusion versus isotonic saline. Magnesium sulfate was associated with statistically decreased variability only in the third hour of the infusion. However, the average decrease in variability was deemed clinically insignificant because the mean variability was 2.7 beats/min in the third hour of magnesium infusion compared with 2.8 beats/min at baseline. Magnesium sulfate also blunted the frequency of accelerations.

It is generally believed that reduced baseline heart rate variability is the single most reliable sign of fetal compromise. For example, Smith and co-workers (1988) performed a computerized analysis of beat-to-beat variability in growth-restricted fetuses before labor. They observed that diminished variability (4.2 beats/min or less) that was maintained for 1 hour was diagnostic of developing acidemia and imminent fetal death. By contrast, Samueloff and associates (1994) evaluated variability as a predictor of fetal outcome during labor in 2200 consecutive deliveries. They concluded that variability by itself cannot be used as the only indicator of fetal well-being. Conversely, they also concluded that good variability should not be interpreted as necessarily reassuring.

In summary, beat-to-beat variability is affected by a variety of pathological and physiological mechanisms. Variability has considerably different meaning depending on the clinical setting. The development of decreased variability in the absence of decelerations is unlikely to be due to fetal hypoxia (Davidson and co-workers, 1992). A persistently flat fetal heart rate baseline—absent variability—within the normal baseline rate range and without decelerations may reflect a previous insult to the fetus that has resulted in neurological damage (Freeman and colleagues, 2003).

Periodic Fetal Heart Rate Changes

The periodic fetal heart rate refers to deviations from baseline that are related to uterine contractions. Acceleration refers to an increase in fetal heart rate above baseline and deceleration to a decrease below baseline rate. The nomenclature most commonly used in the United States is based upon the timing of the deceleration in relation to contractions—thus, early, late, or variable in onset related to the corresponding uterine contraction. The waveform of these decelerations is also significant for pattern recognition. In early and late decelerations, the slope of fetal heart rate change is gradual, resulting in a curvilinear and uniform or symmetrical waveform. With variable decelerations, the slope of fetal heart rate change is abrupt and erratic, giving the waveform a jagged appearance. It has been proposed that decelerations be defined as recurrent if they occur with 50 percent or more of contractions in any 20-minute period (NICHD Research Planning Workshop, 1997).

Another system now used less often for description of decelerations is based on the pathophysiological events considered most likely to cause the pattern. In this system, early decelerations are termed head compression, late decelerations are termed uteroplacental insufficiency, and variable decelerations become cord compression patterns. The nomenclature of type I (early), type II (late), and type III (variable) “dips” proposed by Caldeyro-Barcia and co-workers (1973) is not used in the United States.

Accelerations

An acceleration is a visually apparent abrupt increase—defined as onset of acceleration to a peak in less than 30 seconds—in the fetal heart rate baseline (NICHD Research Planning Workshop, 1997). According to Freeman and co-authors (2003), accelerations most often occur antepartum, in early labor, and in association with variable decelerations. Proposed mechanisms for intrapartum accelerations include fetal movement, stimulation by uterine contractions, umbilical cord occlusion, and fetal stimulation during pelvic examination. Fetal scalp blood sampling and acoustic stimulation also incite fetal heart rate acceleration (Clark and co-workers, 1982). Finally, acceleration can occur during labor without any apparent stimulus. Indeed, accelerations are common in labor and nearly always associated with fetal movement. These accelerations are virtually always reassuring and almost always confirm that the fetus is not acidemic at that time.

Accelerations seem to have the same physiological explanations as beat-to-beat variability in that they represent intact neurohormonal cardiovascular control mechanisms linked to fetal behavioral states. Krebs and co-workers (1982) analyzed electronic heart rate tracings in nearly 2000 fetuses and found sporadic accelerations during labor in 99.8 percent. The presence of fetal heart accelerations during the first or last 30 minutes, or both, was a favorable sign for fetal well-being. The absence of such accelerations during labor, however, is not necessarily an unfavorable sign unless coincidental with other nonreassuring changes. There is about a 50-percent chance of acidemia in the fetus who fails to respond to stimulation in the presence of an otherwise nonreassuring pattern (Clark and colleagues, 1984; Smith and colleagues, 1986).

Early Deceleration

Early deceleration of the fetal heart rate consists of a gradual decrease and return to baseline associated with a contraction (Fig. 18–14). Such early deceleration was first described by Hon (1958). He observed that there was a drop in heart rate with uterine contractions and that this was related to cervical dilatation. He considered these findings to be physiological.

Figure 18–14.image

 

Feature s of early fetal heart rate deceleration. Characteristics include gradual decrease in the heart rate with both onset and recovery coincident with the onset and recovery of the contraction. The nadir of the deceleration is 30 seconds or more after the onset of the deceleration.

Freeman and co-authors (2003) defined early decelerations as those generally seen in active labor between 4 and 7 cm dilatation. In their definition, the degree of deceleration is generally proportional to the contraction strength and rarely falls below 100 to 110 beats/min or 20 to 30 beats/min below baseline. Such decelerations are uncommon during active labor and are not associated with tachycardia, loss of variability, or other fetal heart rate changes. Importantly, early decelerations are not associated with fetal hypoxia, acidemia, or low Apgar scores.

Head compression probably causes vagal nerve activation as a result of dural stimulation and that mediates the heart rate deceleration (Paul and co-workers, 1964). Ball and Parer (1992) concluded that fetal head compression is a likely cause not only of the deceleration shown in Figure 18–14 but also of those shown in Figure 18–15, which typically occur during second-stage labor. Indeed, they observed that head compression is the likely cause of many variable decelerations classically attributed to cord compression.

Figure 18–15.

image

Two different fetal heart rate patterns during second-stage labor that are likely both due to head compression. Maternal bearing-down efforts correspond to the spikes with uterine contractions. Fetal heart rate deceleration C is consistent with the pattern of head compression shown in Figure 18–12. Deceleration B, however, is “variable” in appearance because of its jagged configuration and may also represent cord occlusion.

Late Deceleration

The fetal heart rate response to uterine contractions can be an index of either uterine perfusion or placental function. A late deceleration is a smooth, gradual, symmetrical decrease in fetal heart rate beginning at or after the peak of the contraction and returning to baseline only after the contraction has ended (American College of Obstetricians and Gynecologists, 1995b). In most cases, the onset, nadir, and recovery of the deceleration occur after the beginning, peak, and ending of the contraction, respectively (Fig. 18–16). The magnitude of late decelerations is rarely more than 30 to 40 beats/min below baseline and typically not more than 10 to 20 beats/min. Late decelerations usually are not accompanied by accelerations.

Figure 18–16.

image

Features of late feta l heart rate deceleration. Characteristics include gradual decrease in the heart rate with the nadir and recovery occurring after the end of the contraction. The nadir of the deceleration occurs 30 seconds or more after the onset of the deceleration.

Myers and associates (1973) studied monkeys in which they compromised uteroplacental perfusion by lowering maternal aortic blood pressure. The time interval, or lag period, from the onset of a contraction to the onset of a late deceleration was directly related to basal fetal oxygenation. They demonstrated that the length of the lag phase was predictive of the fetal PO2 but not fetal pH. The lower the fetal PO2 prior to contractions, the shorter the lag phase to onset of late decelerations. This lag period reflected the time necessary for the fetal PO2 to fall below a critical level necessary to stimulate arterial chemoreceptors, which mediated decelerations.

Murata and co-workers (1982) also showed that a late deceleration was the first fetal heart rate consequence of uteroplacental-induced hypoxia. During the course of progressive hypoxia that led to death over 2 to 13 days, the monkey fetuses invariably exhibited late decelerations before the development of acidemia. Variability of the baseline heart rate disappeared as acidemia developed.

A large number of clinical circumstances can result in late decelerations. Generally, any process that causes maternal hypotension, excessive uterine activity, or placental dysfunction can induce late decelerations. The two most common causes are hypotension from epidural analgesia and uterine hyperactivity caused by oxytocin stimulation. Maternal diseases such as hypertension, diabetes, and collagen-vascular disorders can cause chronic placental dysfunction. A rare cause is severe chronic maternal anemia without hypovolemia. Placental abruption can cause acute late decelerations (Fig. 18–17).

Figure 18–17.

image

Late decelerations due to uteroplacental insufficiency resulting from placental abruption. Immediate cesarean delivery was performed. Umbilical artery pH was 7.05 and the PO2 was 11 mm Hg.

Variable Decelerations

The most common deceleration patterns encountered during labor are variable decelerations attributed to umbilical cord occlusion. Melchior and Bernard (1985) identified variable decelerations in 40 percent of over 7000 monitor tracings when labor had progressed to 5 cm dilatation and in 83 percent by the end of the first stage. Variable deceleration of the fetal heart rate is defined as a visually apparent abrupt decrease in rate. The onset of deceleration commonly varies with successive contractions (Fig. 18–18). The duration is less than 2 minutes.

Figure 18–18.

image

Features of variable fetal heart rate decelerations. Characteristics include abrupt decrease in the heart rate with onset commonly varying with successive contractions. The decelerations measure  15 beats/min for 15 seconds or longer with an onset to nadir phase of less than 30 seconds. Total duration is less than 2 minutes.

Very early in the development of electronic monitoring, Hon (1959) tested the effects of umbilical cord compression on fetal heart rate (Fig. 18–19). Similar complete occlusion of the umbilical cord in experimental animals produces abrupt, jagged-appearing deceleration of the fetal heart rate (Fig. 18–20). Concomitantly, fetal aortic pressure increases. Itskovitz and co-workers (1983) observed that variable decelerations in fetal lambs occurred only after umbilical blood flow was reduced by at least 50 percent.

Figure 18–19.

image

Fetal heart rate effects of compression of a prolapsed umbilical cord in a 25-week footling breech. Panel A shows the effects of 25-second compression compared with those of 40 seconds in panel B. (Redrawn from Hon, 1959, with permission.)

Figure 18–20.

image

Total umbilical cord occlusion (arrow) in the sheep fetus is accompanied by increase in fetal aortic blood pressure. Blood pressure changes in the umbilical vessels are also shown. (From Kunzel, 1985, with permission.)

Two types of variable decelerations are shown in Figure 18–21. The deceleration denoted by A is very much like that seen with complete umbilical cord occlusion in experimental animals (see Fig. 18–20). Deceleration B, however, has a different configuration because of the “shoulders” of acceleration before and after the deceleration component. Lee and co-workers (1975) proposed that this variation of variable decelerations was caused by differing degrees of partial cord occlusion. In this physiological scheme, occlusion of only the vein reduces fetal blood return, thereby triggering a baroreceptor-mediated acceleration. Subsequent complete occlusion results in fetal systemic hypertension due to obstruction of umbilical artery flow. This stimulates a baroreceptor-mediated deceleration. Presumably, the aftercoming shoulder of acceleration represents the same events occurring in reverse (Fig. 18–22).

Figure 18–21

image

 

Varying (variable) fetal heart rate decelerations. Deceleration B exhibits “shoulders” of acceleration compared with deceleration A.

Figure 18–22.

image

Schematic representation of the fetal heart rate (FHR) effects of partial occlusion (PO) and complete occlusion (CO) of the umbilical cord. (FSBP = fetal systemic blood pressure; UA = umbilical artery; UC = uterine contraction; UV = umbilical vein.) (From Lee and co-authors, 1975, with permission.)

Ball and Parer (1992) concluded that variable decelerations are mediated vagally and that the vagal response may be due to chemoreceptor or baroreceptor activity, or both. Partial or complete cord occlusion produces an increase in afterload (baroreceptor) and a decrease in fetal arterial oxygen content (chemoreceptor). These both result in vagal activity leading to deceleration. In fetal monkeys the baroreceptor reflexes appear to be operative during the first 15 to 20 seconds of umbilical cord occlusion followed by decline in PO2 at approximately 30 seconds, which then serves as a chemoreceptor stimulus (Mueller-Heubach and Battelli, 1982).

Thus, variable decelerations represent fetal heart rate reflexes that reflect either blood pressure changes due to interruption of umbilical flow or changes in oxygenation. It is likely that most fetuses have experienced brief but recurrent periods of hypoxia due to umbilical cord compression during gestation. The frequency and inevitability of cord occlusion undoubtedly has provided the fetus with these physiological mechanisms as a means of coping. The great dilemma for the obstetrician in managing variable fetal heart rate decelerations is determining when variable decelerations are pathological. The American College of Obstetricians and Gynecologists (1995b) has defined significant variable decelerations as those decreasing to less than 70 beats/min and lasting more than 60 seconds.

Other fetal heart rate patterns have been associated with umbilical cord compression. Saltatory baseline heart rate (Fig. 18–23) was first described by Hammacher and co-workers (1968) and linked to umbilical cord complications during labor. Saltatory derives from the Latin and French words meaning “to leap.” The pattern consists of rapidly recurring couplets of acceleration and deceleration causing relatively large oscillations of the baseline fetal heart rate. We also observed a relationship between cord occlusion and the saltatory pattern (Leveno and associates, 1984). In the absence of other fetal heart rate findings, these do not signal fetal compromise. Lambda is a pattern involving an acceleration followed by a variable deceleration with no acceleration at the end of the deceleration. This pattern typically is seen in early labor and is not ominous (Freeman and colleagues, 2003). This lambda pattern may result from mild cord compression or stretch. Overshoot is a variable deceleration followed by acceleration. The clinical significance of this pattern is controversial (Westgate and colleagues, 2001).

Figure 18–23.

image

Saltatory baseline fetal heart rate showing rapidly recurring couplets of acceleration combined with deceleration.

Prolonged Deceleration

Shown in Figure 18–24, this pattern is defined as an isolated deceleration lasting 2 minutes or longer but less than 10 minutes from onset to return to baseline (NICHD Research Planning Workshop, 1997). Prolonged decelerations are difficult to interpret because they are seen in many different clinical situations. Some of the more common causes include cervical examination, uterine hyperactivity, cord entanglement, and maternal supine hypotension.

Figure 18–24.

image

Prolonged fetal heart rate deceleration due to uterine hyperactivity. Approximately 3 minutes of the tracing are shown, but the fetal heart rate returned to normal after uterine hypertonus resolved. Vaginal delivery later ensued.

Epidural, spinal, or paracervical analgesia may induce prolonged deceleration of the fetal heart rate. For example, Eberle and colleagues (1998) reported that prolonged decelerations occurred in 4 percent of normal parturients given either epidural or intrathecal labor analgesia. Hill and colleagues (2003) observed prolonged deceleration in 1 percent of women given epidural analgesia during labor at Parkland Hospital. Other causes of prolonged deceleration include maternal hypoperfusion or hypoxia from any cause, placental abruption, umbilical cord knots or prolapse, maternal seizures including eclampsia and epilepsy, application of a fetal scalp electrode, impending birth, or even maternal Valsalva maneuver.

The placenta is very effective in resuscitating the fetus if the original insult does not recur immediately. Occasionally, such self-limited prolonged decelerations are followed by loss of beat-to-beat variability, baseline tachycardia, and even a period of late decelerations, all of which resolve as the fetus recovers. Freeman and co-authors (2003) emphasize rightfully that the fetus may die during prolonged decelerations. Thus, management of prolonged decelerations can be extremely tenuous. Management of isolated prolonged decelerations is based upon bedside clinical judgment, which inevitably will sometimes be imperfect given the unpredictability of these decelerations.

 

 


Table 18–5. Guidelines for Intrapartum Fetal Heart Rate Surveillance

 

Surveillance Low-Risk Pregnancies High-Risk Pregnancies
Acceptable methods
  Intermittent auscultation Yes Yes
  Continuous electronic monitoring (internal or external) Yes Yes
Evaluation intervalsa
  First-stage labor (active) 30 min 15 minb
  Second-stage labor 15 min 5 minb

aFollowing a uterine contraction.

bIncludes tracing evaluation and charting when continuous electronic monitoring is used.

Adapted from the American College of Obstetricians and Gynecologists (1995b).

 


Table 18–1. NICHD Research Planning Workshop (1997) Fetal Heart Rate Patterns

 

Pattern Workshop Interpretations
Normal Baseline 110–160 beats/min
Variability 6–25 beats/min
Accelerations present
No decelerations
Intermediate No consensus
Severely abnormal Recurrent late or variable decelerations with zero variability
Substantial bradycardia with zero variability

4. Doppler Velocimetry

The Doppler shift is a phenomenon that occurs when a source of light or sound waves is moving relative to an observer; the observer detects a shift in the wave frequency. Similarly, when sound waves strike a moving target, the frequency of the sound waves reflected back is shifted proportionate to the velocity and direction of the moving target. Because the magnitude and direction of the frequency shift depend on the relative motion of the moving target, the velocity and direction of the target can be determined.

Important to obstetrics, Doppler may be used to determine the volume and rate of blood flow through maternal and fetal vessels. In this situation, the sound source is the ultrasound transducer, the moving target is the column of red blood cells flowing through the circulation, and the reflected sound waves are observed by the ultrasound transducer. Two types—continuous and pulse wave Doppler—are used in medicine.

Continuous wave Doppler equipment has separate crystals: one that transmits a high-frequency sound wave, and another that continuously receives signals. It can record high frequencies using low power output and is easy to use. Unfortunately, it is nonselective, recognizing all signals along its path, and does not allow visualization of the blood vessel(s). In m-mode echocardiography, continuous wave Doppler is used to evaluate motion through time. It defines blood flow through the heart, but because the cardiac structures are not visualized, it requires the correlation of the sequence of waveforms produced with the sequence of structures interrogated by the sound wave.

Pulse wave Doppler has equipment that uses only one crystal, which transmits the signal and then waits until the returning signal is received before transmitting another one. It is more expensive and requires higher power, but allows precise targeting and visualization of the vessel of interest. Pulse wave Doppler also can be configured to allow color-flow mapping, in which computer software displays blood flowing away from the transducer as blue and blood flowing toward the transducer as red.

Various combinations of continuous wave Doppler, pulse wave Doppler, color-flow Doppler, and real-time ultrasound are commercially available and are loosely referred to as duplex Doppler.

Clinical Applications

The Doppler equation shown in Figure 16–17 contains the variables that affect the Doppler shift. An important source of error when calculating flow or velocity is the angle between sound waves from the transducer and flow within the vessel—termed the angle of insonation and abbreviated as theta (). Because cosine  is a component of the equation, measurement error becomes large when the angle of insonation is not close to zero. The practical solution to this problem has been the use of ratios to compare different waveform components—allowing cosine  to cancel out of the equation. Figure 16–18 is a schematic of the Doppler waveform and describes the three ratios commonly used. The simplest is the systolic–diastolic ratio (S/D ratio), which compares maximum (peak) systolic flow with end-diastolic flow, thereby evaluating downstream impedance to flow.

 

image

image

Doppler waveforms from normal pregnancy. Shown clockwise are normal waveforms from the maternal arcuate, uterine, and external iliac arteries, and from the fetal umbilical artery and descending aorta. Reversed end-diastolic flow velocity is apparent in the external iliac artery, whereas continuous diastolic flow characterizes the uterine and arcuate vessels. Finally, note the greatly diminished end-diastolic flow in the fetal descending aorta. (From Copel and colleagues, 1988.)

Umbilical Artery

This vessel normally has forward flow throughout the cardiac cycle, and the amount of flow during diastole increases as gestation advances. Thus the S/D ratio decreases, from about 4.0 at 20 weeks to 2.0 at term. The S/D ratio is generally less than 3.0 after 30 weeks (Fleischer and associates, 1986). Umbilical artery Doppler may be a useful adjunct in the management of pregnancies complicated by fetal growth restriction. As presented in Chapter 15 (see Umbilical Artery Doppler Velocimetry), umbilical artery velocimetry has been subjected to more rigorous assessment than has any previous test of fetal health (Alfirevic and Neilson, 1995). It is, however, not recommended for screening of low-risk pregnancies or for complications other than growth restriction.

Umbilical artery Doppler is considered abnormal if the S/D ratio is above the 95th percentile for gestational age. In extreme cases of growth restriction, end-diastolic flow may become absent or even reversed (Fig. 16–20). These are ominous findings and should prompt a complete fetal evaluation—almost half of cases are due to fetal aneuploidy or a major anomaly (Wenstrom and associates, 1991). In the absence of a reversible maternal complication or a fetal anomaly, reversed end-diastolic flow suggests severe fetal circulatory compromise and usually prompts immediate delivery. Sezik and colleagues (2004) recently reported that fetuses of preeclamptic women who had absent or reversed end-diastolic flow were more likely to have hypoglycemia and polycythemia.

image

Umbilical artery Doppler waveforms. A. Normal diastolic flow. B. Absence of end-diastolic flow. C. Reversed end-diastolic flow. (Courtesy of Dr. Diane Twickler.)

Ductus Arteriosus

Doppler evaluation of the ductus arteriosus has been used primarily to monitor fetuses exposed to indomethacin and other nonsteroidal anti-inflammatory agents. Indomethacin, which is used for tocolysis, causes constriction of the ductus in sheep and human fetuses (Huhta and colleagues (1987). The resulting increased pulmonary flow may cause reactive hypertrophy of the pulmonary arterioles, and eventually pulmonary hypertension develops (see Chap. 36, Prostaglandin Inhibitors). In a study of 61 indomethacin-treated pregnant women, Vermillion and colleagues (1997) reported that half of exposed fetuses developed ductal constriction. Fortunately, this complication is largely reversible if medication is discontinued before 32 weeks (Moise, 1993).

Middle Cerebral Artery

Peak systolic velocity in the middle cerebral artery is increased with fetal anemia because of increased cardiac output and decreased blood viscosity (Segata and Mari, 2004). Velocity measurements are generally problematic because a high insonating angle introduces considerable error. Middle cerebral artery measurements are an exception, however, because the path of the artery often presents a very low angle of insonation.

Mari and colleagues (1995) performed velocity studies in 135 normal fetuses and 39 with alloimmunization. They reported that all anemic fetuses had peak systolic velocity above the normal mean. This prompted a collaborative study of 376 pregnancies by Mari and colleagues (2000). Using a threshold of 1.50 multiples of the median (MoM), they correctly identified all fetuses with moderate or severe anemia with a false-positive rate of 12 percent. Other investigators have since reported similar results (Abdel-Fattah, 2002; Bahado-Singh, 2000; Cosmi, 2002; Deren and Onderoglu, 2002, and all their associates).

It also has been hypothesized that Doppler evaluation of blood flow through cerebral vessels might be used to detect altered cerebral circulation before there is hypoxemia significant enough to alter the fetal heart rate pattern. The cerebroplacental ratio has been introduced as an indicator of brain sparing in fetuses with growth restriction and as a predictor of adverse perinatal outcome (Bahado-Singh and colleagues, 1999; Gramellini and associates, 1992). Currently, the American College of Obstetricians and Gynecologists (1999) considers antepartum surveillance with cerebral artery Doppler velocimetry to be investigational.

Uterine Artery

Uterine blood flow increases from 50 mL/min early in gestation to 500 to 750 mL/min by term. The uterine artery Doppler waveform is unique and characterized by high diastolic flow velocities similar to those in systole, and by highly turbulent flow, which displays a spectrum of many different velocities (Fig. 16–21). Increased resistance to flow and development of a diastolic notch have been associated with pregnancy-induced hypertension (Arduini, 1987; Fleischer, 1986; Harrington, 1996; North, 1994, and all their colleagues). In a recent study, Zeeman and co-authors (2003) confirmed that increased impedance of uterine artery velocimetry at 16 to 20 weeks was predictive of superimposed preeclampsia developing in women with chronic hypertension. Whether it will be clinically helpful to predict preeclampsia in this manner is yet unclear.

5. Screening for Common Congenital Abnormalities

The vast majority of cases of NTDs, Down syndrome, and many other fetal abnormalities are found in families with no prior history of birth defects. Prenatal evaluation of only women at high risk for these complications would thus fail to identify most affected pregnancies. Couples with no family history of genetic abnormalities can now be offered prenatal screening tests for certain fetal disorders. Screening tests by design do not provide a diagnosis, but rather identify individuals with risk high enough to benefit from a definitive diagnostic test. According to Wald and associates (1997), genetic screening tests should meet criteria generally accepted for other types of screening tests:

  1. The disorder is well defined and serious.
  2. Treatment or prevention is available but not possible without the screening test.
  3. The screening test is cost effective and reliable.
  4. The subsequent diagnostic test is reliable.

That said, Caughey and collaborators (2004) interviewed 447 women of all ages with undetermined genetic risk. They reported that half were willing to undergo invasive prenatal diagnostic testing. One third of women aged 35 years or older expressed a willingness to pay partially or completely for such testing. Such requests present a conundrum for prenatal diagnostic centers and each should have a protocol to cover these exigencies.

Neural-Tube Defects (NTDs)

At least 95 percent of children with NTDs are born into families with no prior history. Prior to the late 1970s, identification of affected pregnancies was not possible. At that time, Brock and associates (1972, 1973) reported that both amnionic fluid and maternal serum alpha-fetoprotein (AFP) levels were much higher in pregnancies complicated by fetal anencephaly and other NTDs. The first large prospective trial of maternal serum screening was the UK Collaborative Study on Alpha-fetoprotein in Relation to Neural-tube Defects (1977). The utility of maternal serum AFP screening for NTDs was subsequently confirmed by others and adopted in the United States and Europe (Burton and associates, 1983; Haddow and colleagues, 1983; Milunsky and co-workers, 1980).

Alpha-Fetoprotein (AFP)

This glycoprotein is synthesized early in gestation by the fetal yolk sac and later by the fetal gastrointestinal tract and liver (see Chap. 4). It normally circulates in fetal serum and passes into fetal urine and thus into amnionic fluid. Although its function is unknown, AFP is the major serum protein in the embryo-fetus, analogous to albumin. Its concentration increases steadily in both fetal serum and amnionic fluid until 13 weeks, after which these levels rapidly decrease (Burton, 1988). AFP passes into the maternal circulation by diffusion across the placental membranes and also may be transported via the placental circulation (Brumfield and colleagues, 1990). AFP is found in steadily increasing quantities in maternal serum after 12 weeks (Fig. 13–2). Open fetal body wall defects uncovered by integument permit additional AFP to leak into the amnionic fluid, and maternal serum AFP levels are increased.

Maternal Serum AFP Screening

Maternal screening is offered between 14 and 22 weeks. Maternal serum AFP is measured in nanograms per milliliter and reported as a multiple of the median (MoM) of the unaffected population. Converting the results to MoM normalizes the distribution of AFP levels and permits comparison of results from different laboratories and populations. Factors that influence the maternal serum AFP level include weight, race, and diabetic status, as well as the gestational age and number of fetuses. Using a maternal serum AFP level of 2.0 or 2.5 MoM as the upper limit of normal, most laboratories report a screen-positive rate of 3 to 5 percent, a sensitivity of at least 90 percent, and a positive-predictive value of 2 to 6 percent (Milunsky and associates, 1989).

Evaluation of an elevated maternal serum AFP begins with a basic ultrasonographic examination to determine fetal age and viability and the number of fetuses (Fig. 13–3). Underestimating gestational age accounts for a large proportion of abnormal test results. In such cases, the laboratory can usually generate a corrected report when given accurate pregnancy dating criteria. If the initial specimen was obtained prior to 14 weeks, a repeated specimen is necessary. The distributions of maternal serum AFP levels in affected and unaffected pregnancies overlap considerably (Fig. 13–4). If the level falls within the range of the overlap—the indiscriminate zone of 2.5 to 3.5 MoM—then repeating the measurement may determine whether the pregnancy is really at risk. Because repeated measurements tend to regress toward the mean of the population to which they belong, a truly elevated maternal serum AFP level will remain so in the repeated sample, whereas levels from an unaffected pregnancy have a tendency to normalize .

Maternal serum AFP levels greater than 3.5 MoM need not be repeated, because levels this high are outside the AFP distribution of unaffected pregnancies and clearly indicate increased fetal risk. In general, the likelihood that the fetus is affected increases in proportion to the AFP level. In a study of 773 women with elevated serum AFP levels, Reichler and colleagues (1994) reported that there was a progressive increase in the frequency of NTDs, ventral wall defects, and other anomalies as maternal serum AFP levels rose (Fig. 13–5). About 40 percent of pregnancies were abnormal when the AFP level was greater than 7 MoM.

Other causes of elevated levels that can be determined by ultrasonography include fetal death, multiple gestations, structural defects, and placental abnormalities

Table 13–7. Conditions Associated with Abnormal Maternal Serum Alpha-Fetoprotein Concentrations

Elevated Levels

Neural-tube defects

Pilonidal cysts

Esophageal or intestinal obstruction

Liver necrosis

Cystic hygroma

Sacrococcygeal teratoma

Abdominal wall defects—omphalocele, gastroschisis

Urinary obstruction

Renal anomalies—polycystic or absent kidneys

Congenital nephrosis

Osteogenesis imperfecta

Congenital skin defects

Cloacal exstrophy

Chorioangioma of placenta

Placental abruption

Placenta accreta

Oligohydramnios

Preeclampsia

  Multifetal gestation

Low birthweight

  Fetal death

Improper adjustment for low maternal weight

Underestimated gestational age

Maternal hepatoma or teratoma

Low Levels

Chromosomal trisomies

Gestational trophoblastic disease

Fetal death

Improper adjustment for high maternal weight

Overestimated gestational age

Recommendations for Screening

The American College of Obstetricians and Gynecologists (2003) recommends that all pregnant women be offered second-trimester maternal serum AFP screening. It should be performed within a protocol that includes quality control, counseling, follow-up, and high-resolution ultrasonography. Because only 1 in 16 to 1 in 33 women with an elevated serum AFP level actually has an affected fetus, women should be counseled regarding the high false-positive rates, the risks of amniocentesis, and the rationale for the screening program.

Ultrasonographic Examination

After confirming the gestational age and establishing fetal number and viability, the fetus is evaluated by targeted ultrasonography. Anencephaly, other major cranial defects, and most spine defects can be readily identified (Figs. 13–6 and 13–7). In 99 percent of cases, open spine lesions are associated with one or more of five specific cranial anomalies detected by ultrasonography (Watson and associates, 1991). As detailed in Chapter 16 (see Neural-Tube Defects), these include frontal notching, also called the lemon sign; small biparietal diameter; ventriculomegaly; obliteration of the cisterna magna; and elongated cerebellum, the banana sign (Fig. 13–8). These cranial anomalies are most clearly visible in the second trimester, and some, such as the lemon sign, may resolve later in pregnancy.

image

Cranial ultrasound in a fetus with Arnold–Chiari malformation showing frontal scalloping (lemon sign) on the left and effacement of the cisterna magna (banana sign) on the right. (Courtesy of Dr. Jodi Dashe.)

In the early days of AFP screening, an elevated maternal serum AFP level prompted amniocentesis to determine the amnionic fluid AFP level. If the AFP level was elevated, then an assay for acetylcholinesterase was done. These tests were considered diagnostic for fetal NTD. Today, however, nearly 100 percent of NTDs are identified by ultrasonography used alone (Nadel and colleagues, 1990; Sepulveda and associates, 1995). Citing this high detection rate, several authorities conclude that a woman with an elevated maternal serum AFP level and a normal ultrasonographic examination need not undergo amniocentesis for amnionic fluid AFP measurement. Instead, she could be counseled that the risk of an NTD is reduced by 95 percent when no spine defects or cranial findings are seen ultrasonographically (Hogge, 1989; Morrow, 1991; Van den Hof, 1990, and their colleagues).

By contrast, a number of other studies report considerably less than a 100-percent ultrasonographic detection rate for structural fetal anomalies, especially before 22 weeks. For example, only 17 percent of all fetal anomalies were identified in the Routine Antenatal Diagnostic Imaging with Ultrasound (RADIUS) trial (Chap. 16, Clinical Applications). VanDorsten and colleagues (1998) reported only a 48-percent ultrasonographic detection rate for all fetal anomalies diagnosed. Platt and co-workers (1992) reported that 6 of 161 cases of open spina bifida were not recognized in a screening program. Accordingly, many recommend that an amniocentesis for amnionic fluid AFP be offered to all women with elevated maternal serum AFP levels. Women considering amniocentesis should be informed that amnionic fluid AFP measurement will detect only open spine defects, and not the 3 to 5 percent of defects that are covered by skin (Crandall and Matsumoto, 1984).

Amniocentesis

Amnionic fluid AFP levels are measured if an NTD is suspected, if the maternal serum AFP is elevated and the ultrasonographic examination is nondiagnostic, or simply because the maternal serum AFP is elevated, as discussed previously. An elevated amnionic fluid AFP level prompts assay of the same sample for acetylcholinesterase. After ruling out blood contamination, the presence of this enzyme verifies that exposed neural tissue or another open fetal defect is present.

Because NTDs carry a small associated risk of aneuploidy, and aneuploidy would change the prognosis and likely pregnancy management, ultrasonographic identification of a fetal NTD should prompt fetal karyotyping. In a review of more than 17,000 prenatal diagnosis cases, Hume and associates (1996) observed a 2-percent rate of aneuploidy in the 106 fetuses with an isolated NTD. Harmon and colleagues (1995) found that 7 of 43 fetuses with isolated NTDs were aneuploid.

Some clinicians determine the fetal karyotype whenever both maternal serum and amnionic fluid AFP levels are elevated, even if the amnionic fluid acetylcholinesterase assay is negative and an open NTD has thus been ruled out. Gonzalez and associates (1996) reported that in women with elevated serum and amnionic fluid AFP levels and normal ultrasonographic examinations, the incidence of chromosomal abnormalities was elevated fivefold above background risk.

Incidental Fetal Karyotype

If a woman with a normal targeted ultrasonographic examination has undergone amniocentesis for amnionic fluid AFP just because her maternal serum AFP level was elevated, and the amnionic fluid AFP level is normal, fetal karyotyping is controversial. Thiagarajah and colleagues (1995) studied 658 such women and concluded that there was no justification for routine fetal karyotyping. In contrast, Feuchtbaum and associates (1995) reviewed 8097 pregnancies complicated by elevated maternal serum AFP levels. In the pregnancies in which the elevated maternal serum AFP level was “unexplained” because there was no fetal NTD or ventral wall defect and the amnionic fluid AFP level was normal, the rate of chromosomal anomalies was 1.1 percent, or twice as high as that of the general population.

Incidental Amnionic Fluid AFP Measurement

When amniocentesis is performed primarily for genetic analysis, amnionic fluid AFP is often routinely measured. This practice may not be cost-effective. Shields and colleagues (1996) reviewed almost 7000 women who underwent second-trimester amniocentesis for fetal karyotyping. They reported that measurement of amnionic fluid AFP did not increase the detection of anomalies. Similarly, Silver and associates (2001) performed a retrospective analysis of 2769 amnionic fluid specimens and reported that incidental amnionic fluid AFP measurement identified only one NTD not detected by ultrasonography. They estimated that routine amnionic fluid AFP measurement cost $219,000 per informative case.

Unexplained Elevated Abnormal Maternal Serum AFP Levels

Even if there are no obvious fetal abnormalities, several large studies have shown that unexplained high maternal serum AFP levels often forecast a poor pregnancy outcome. These outcomes include low birthweight, oligohydramnios, placental abruption, and fetal death (Katz, 1990; Simpson, 1991; Waller, 1991, each with their associates). According to Wenstrom and co-workers (1992), the first maternal serum AFP level is the most predictive, and serial measurements are not helpful. Simpson and colleagues (1991) reported that second-trimester, but not third-trimester, maternal serum AFP elevation levels were associated with preterm ruptured membranes, preterm birth, and low-birthweight infants. Ramus and associates (1996) studied 241 women with unexplained serum AFP elevations and reported that they had a higher incidence of preterm delivery than women who had normal levels—22 versus 11 percent. The incidence of preterm delivery was highest (47 percent) in the 38 women who had both unexplained elevated serum levels and placental sonolucencies on ultrasonographic examination.

Although elevated maternal serum AFP levels in these cases are assumed to result from placental damage or dysfunction, neither the etiology of the elevated maternal serum values nor the most appropriate management for these women is clear. In these cases, no specific program of maternal or fetal surveillance favorably affects pregnancy outcomes (American College of Obstetricians and Gynecologists, 1996; Cunningham and Gilstrap, 1991).

Management of the Fetus with an NTD

Other than termination of pregnancy, options for pregnancies complicated by an NTD have traditionally been limited. Anencephaly, exencephaly, and iniencephaly are lethal, but some women elect to continue these pregnancies. Routine prenatal care is given, but interventions for fetal indications are not recommended as they will not change fetal outcome.

Counseling and decision making in the case of an isolated fetal spine defect are more difficult. Such women may benefit from counseling by a pediatric neurosurgeon, neurologist, or other specialists in pediatric development. The fully informed couple is more likely to make their best decision and to be prepared for the range of possible pregnancy outcomes. With continued pregnancy, antenatal care is designed to detect changes in fetal status that might alter the timing or route of delivery. Generally, the goal is delivery at term, but rapidly increasing ventriculomegaly may prompt delivery before term so that a shunt can be placed. Fetal heart rate testing is problematic because heart rate patterns in anomalous fetuses can be difficult to interpret (Vindla and associates, 1997).

The optimal timing and method of delivery remain controversial. All studies of delivery methods for fetuses with NTDs are retrospective and suffer from various biases. That said, an equal number of reports support cesarean versus vaginal delivery (Bensen and co-workers, 1988; Luthy and colleagues, 1991; Sakala and Andree, 1990). Theoretically, cesarean delivery might reduce the risk of mechanical trauma and infection of the fetal spine and also allow precise timing of delivery so that appropriate consultants can be available. Optimally, the delivery time and method should be determined on a case-by-case basis by the team that ultimately will care for the woman and her neonate. Team members should include maternal–fetal medicine specialists, neonatologists, neurosurgeons, and others. Fetal surgical repair of meningomyelocele is discussed later (see Neural-Tube Defects).

Down Syndrome

Before the mid-1980s, amniocentesis for fetal karyotyping was generally offered only to women aged 35 years and older. After Merkatz and colleagues (1984) reported that pregnancies with fetal Down syndrome were characterized by low maternal serum AFP levels, prenatal NTD screening was expanded to include Down syndrome screening in women aged younger than 35 years. Cuckle (1984) and Haddow (1983) and their associates confirmed this finding, and most NTD screening programs now include Down syndrome screening.

Screening program results show that detection rates are highest when maternal age-related risk is incorporated because it is the most powerful predictor of aneuploidy. Ultimately, the Down syndrome risk for each woman is estimated by multiplying her maternal age-related risk by a likelihood ratio determined by her serum AFP level (New England Regional Genetics Group, 1989). Women with a calculated Down syndrome risk greater than a predetermined threshold are offered amniocentesis for fetal karyotyping. This screening threshold is typically equal to the midtrimester or term Down syndrome risk of a 35-year-old woman.

Multiple-Marker Screening

Fetal aneuploidy alters serum analytes other than AFP. If a fetus has Down syndrome, second-trimester serum levels of chorionic gonadotropin (hCG) are usually higher and those of unconjugated estriol are lower than expected (Bogart and colleagues, 1987; Wald and associates, 1988a, 1988b). The individual predictive values of hCG, estriol, and AFP for detecting Down syndrome are low, but when combined they can frequently distinguish euploid fetuses from those with Down syndrome.

The most common second-trimester screening protocol in current use, variously called the expanded AFP test, AFP plus, triple screen, or multiple-marker screening test, is based on a composite likelihood ratio determined by levels of all three analytes. The maternal age-related risk is then multiplied by this ratio. The screening threshold chosen may be the midtrimester risk of a 35-year-old woman. More frequently, a threshold is chosen because it results in the optimal combination of a high detection rate with a low screen-positive rate. The risk threshold of about 1:200 is selected most often because, at a 5-percent screen-positive rate, the Down syndrome detection rate is 60 percent in women younger than 35 years. In women older than 35 years, the multiple-marker test detects more than 75 percent of fetuses with Down syndrome and a portion of other aneuploidies as well, although at a detection rate close to 25 percent (Haddow and co-workers, 1994). The multiple-marker test has been validated and has become the preferred second-trimester Down syndrome screening test in most centers (Burton, 1993; Cheng, 1993; Wenstrom, 1993, and their colleagues).

There are several permutations of the multiple-marker test in current use. Some centers offer AFP and hCG testing alone, and others use estriol measurement as a third marker. Some prefer to measure the free -subunit of hCG (-hCG) instead of the intact hCG molecule, and others add inhibin as a fourth analyte (Wald and colleagues, 1996; Wenstrom and associates, 1999b). Other multiple-marker screening tests have been used that combine maternal serum analytes, ultrasonographic measurement of the nuchal fold, long bone measurements, and other parameters (Bahado-Singh and colleagues, 2001; Morris and co-workers, 2001). Several investigative protocols are subsequently discussed.

In most series, only 6 percent of all screen-positive samples are associated with an affected fetus. Thus, a positive screening test indicates increased risk but not necessarily fetal Down syndrome. Conversely, a negative screening test indicates no increased risk, but does not mean that the fetus is normal. Once gestational age is confirmed by ultrasonography, women with a positive screening test should be offered amniocentesis for karyotyping (American College of Obstetricians and Gynecologists, 1996).

Serum Screening in Women Older Than 35 Years

The basis of any multiple-marker algorithm is the maternal age-related risk. Thus, the multiple-marker screening test identifies a higher proportion of fetal Down syndrome cases—at least 80 percent—in women aged 35 years and older than in younger women (Haddow and co-workers, 1994). Although the detection rate increases along with maternal age, so does the screen-positive rate. For example, about 25 percent of women aged 35 years and older will have a test result indicating increased risk. Although some older women will opt for empirical amniocentesis regardless of screening results, others find that serum screening facilitates the decision to undergo invasive testing.

First-Trimester Down Syndrome Screening

Early identification of fetal aneuploidy is desirable for many reasons, including the availability of more options for pregnancy termination. First-trimester screening protocols in current use include maternal serum analyte screening, ultrasonographic evaluation, or a combination of both. Urinary screening has been studied, but the results were disappointing. The most discriminatory first-trimester maternal serum analytes appear to be free -hCG and pregnancy-associated plasma protein A (PAPP-A) (Haddow and associates, 1998; Wald and colleagues, 1998). Measurement of the nuchal translucency (NT), an echolucent area seen in longitudinal views of the back of the neck, is also highly discriminatory (Snijders and colleagues, 1998). If the NT measurement is expressed as an MoM, it can be combined with serum analytes to calculate a composite risk.

Two large trials of combined first-trimester ultrasonographic and serum screening have documented its efficacy. First Trimester Maternal Serum Biochemistry and Fetal Nuchal Translucency Screening Study, referred to as the “BUN study,” reported by Wapner and co-workers (2003) was a multicenter trial that enrolled 8514 women who underwent screening between 74 and 97 days of gestation. Individual risks of fetal Down syndrome and trisomy 18 were calculated based on age, first-trimester levels of free -hCG and PAPP-A, and NT measurement. Women determined to be screen positive were offered fetal karyotyping. Using a Down syndrome risk cutoff of 1:270, 85 percent of Down syndrome cases were identified at a false-positive rate of 9.4 percent. When the false-positive rate was held at 5 percent, the detection rate was 79 percent. Importantly, 91 percent of trisomy 18 cases were identified at a false-positive rate of 2 percent. Because of the high incidence of spontaneous pregnancy loss in aneuploid pregnancies, performing fetal karyotyping after first-trimester screening likely resulted in the identification of some aneuploid pregnancies that would otherwise have been lost spontaneously. This outcome can be viewed either positively or negatively.

The FASTER (First- and Second-Trimester Evaluation of Risk) trial was reported by Malone and colleagues (2003a, 2003b). This multicenter trial included 33,557 women, and it took a slightly different approach. All women participating in the trial underwent both first-trimester screening—which included free -hCG, PAPP-A, NT measurement, and maternal age—and second-trimester screening with hCG, AFP, estriol, and inhibin, along with maternal age. If either test was positive, fetal karyotyping was offered. The investigators then evaluated the screen-positive and detection rates for first-, second-, and combined first- and second-trimester screening. They found that the best results were obtained when women had combined both first- and second-trimester screening—the Fully Integrated Test—and then underwent definitive testing if its result was positive. The integrated test yielded a Down syndrome detection rate of 90 percent at a screen-positive rate of 5.4 percent. Importantly, the investigators determined that NT measurement was difficult to do accurately and reproducibly (D’Alton and associates, 2003). Further, not only did NT measurement medians vary from center to center and operator to operator, but NT medians obtained by a single operator varied over time. The authors therefore concluded that NT measurement should be performed only by operators with specific training and that measurement medians for individual operators should be monitored carefully and adjusted as necessary.

In addition to drifting NT medians, problems with first-trimester screening include a relatively narrow gestational age window for screening—approximately 10 to 13 weeks—and variability in NT measurement resulting from poor visibility, suboptimal fetal position, or inconsistent measurement technique. Accurate assessment of gestational age is essential. The American College Obstetricians (2004) emphasizes that appropriate training, monitoring systems, and counseling must be provided.

Elective Genetic Amniocentesis in Women Younger Than 35 Years

Some women younger than 35 years may request amniocentesis for fetal karyotyping despite reassuring maternal serum screening and ultrasonographic findings. Caughey and colleagues (2004) interviewed 447 women of all ages with undetermined genetic risk and reported that half were willing to undergo invasive prenatal diagnostic testing. One third of women aged 35 years or older expressed a willingness to pay partially or completely for such testing. These investigators concluded that guidelines should be expanded to offer testing for a genetic diagnosis, not only for screening. Others believe that each case must be evaluated individually, and each center must develop its own protocol to handle such requests (Pauker and Pauker, 1994).

Posted in Medical | Tagged: , , , , , , | 12 Comments »

Orthopaedics MCQs

Posted by Dr KAMAL DEEP on January 17, 2011

Q1.Non dynamic splint is – a) Banjo b) Opponons c) Cock-up d) Brand

Cock-up:-

ACfU3U3PyQGwM0q3YsVHfNCMRE4MwUAb3A

Principles of treatment Ref:- Chapman Ortho

Radial Nerve Palsy:-

The importance of maintaining supple joints free of deformity cannot be overemphasized. Use splints and physical therapy while awaiting nerve recovery and before considering tendon transfers. Splinting must be individualized. A simple palmar cock-up splint may increase the grip strength 3 to 5 times . Most patients are well served by such a splint. A patient requiring greater excursion of the fingers may prefer a dynamic splint with extension assists for the wrist and metacarpophalangeal joints.

dynamic splint

2.Commonest fractures in childhood is – a) Femur b) Distal humerus
c) Clavicle d) Radius

Posted in Medical | Tagged: , , , , , , , , | 1 Comment »

Anatomy Notes Vol.2

Posted by Dr KAMAL DEEP on December 19, 2010

1.  Nerves of Upper Limbs

image

image

2. Musculocutaneous Nerve Supplies Lateral Side of Forearm Also.

image

image

Important See the Diagram:- All muscles of thumb are supplied (pollicis) are supplied by Median Nerve except which causes adduction(Ulnar Nerve)..Obviously Ulnar nerve is a medial nerve it supplies the Adductor Pollicis as adduction is towards medial.

Q:-Median nerve supplies all muscles of the thumb except :
(A)Abductor-pollicis-brevis
(B)Flexor-pollicis brevis
(C)Opponens pollicis
(D)Adductor pollicis…….ans

Median nerve injury at “wrist”, is commonly tested by :-
(A)
Contraction of abductor pollicis brevis…….ans
(B)Contraction of flexor pollicis brevis
(C)Loss of sensation on palm
(D)Loss of sensation on ring finger

The median nerve is vulnerable to division from lacerations at the wrist. Division leads to paralysis of the lumbricals to the index and middle fingers and the thenar muscles (apart from adductor pollicis), as well as loss of sensation to the thumb, index, middle and radial half of the ring fingers. The radial half of the hand becomes flattened as a result of wasting of the thenar muscles and the adducted posture of the thumb.

Pen Test :- Detects the median Nerve injury.It tests the integrity of abductor pollicis brevis

 

First and Second Lumbricals are Also supplied by Median Nerve

Rest all intrinsic muscles including all interossie are supplied by ULNAR NERVE.

Flexor Pollicis Brevis Superficial head supplied by Median Nerve while deep head by Ulnar Nerve.

Flexor Pollicis “Longus” supplied by Median Nerve.

image

Radial Nerve supplies all the extensors and also the ABDUCTOR POLLICIS “LONGUS.”

Pollicis “Longus” muscles are supplied by respective chief muscles of forearm like abductor pollicis longus by radial nerve and flexor pollicis longus by median nerve.

ULNAR NERVE (Musician nerve)IS CHIEF MUSCLE OF HAND.

RADIAL NERVE IS CHIEF MUSCLE OF BACK OF FOREARM

MEDIAN NERVE (Laborers nerve)IS CHIEF MUSCLE OF FRONT OF FOREARM.

3. Ring Finger tip supplied by Median nerve and Ulnar Nerve

4.Dorsum of middle finger is supplied by radial nerve and ulnar nerve and median nerve.

5.Deltoid Muscle Origin is Just outer to the Insertion of Trapezius muscle:-

Origin of Deltoid:-Inferior edge of the crest of the spine of the scapula, lateral margin of the acromion, anterior border of lateral one-third of clavicle

Insertion of Trapezius:-Superior edge of the crest of the spine of the scapula, acromion, posterior border of lateral one-third of clavicle

Function of Deltoid:-Major abductor of arm (abducts arm beyond initial 15° done by supraspinatus); clavicular fibers (Anterior Fibers) assist in flexing the arm; posterior fibers assist in extending the arm.

All of the following features can be observed after the injury to axillary nerve, except:
A.Loss of rounded contour of shoulder
B.Loss of sensation along lateral side of upper arm
C.Loss of overhead abduction
D.Atrophy of deltoid muscle

6. Sub acromial bursa:-

All of the following structures may be compressed during flexion and abduction of shoulder joint except :
(A)Suprascapular nerve
(B)Long head of biceps tendon
(C)Supraspinatus tendon
(D)Subacromial-bursa

clip_image002

Coronal section through the left shoulder joint

Rotator cuff impingement syndrome

The Subacromial space is defined by the humeral head inferiorly, and the anterior edge and inferior surface of the anterior third of the acromion, coracoacromial ligament and acromioclavicular joint superiorly. It is occupied by the supraspinatus tendon, subacromial bursa, tendon of the long head of biceps brachii, and the capsule of the shoulder joint. Rotator cuff impingement syndrome is a painful disorder caused by severe or chronic impingement of the rotator cuff tendons under the coracoacromial arch (Michiner et al 2003). The cuff normally impinges against the coracoacromial arch when the humerus is abducted, flexed and internally rotated. This is known as the impingement position. The supraspinatus tendon is anatomically affected most by the impingement, which interestingly also coincides with an area of reduced vascularity in this tendon. Severe impingement can be caused by osteoarthritic thickening of the coracoacromial arch; inflammation of the cuff from disorders such as rheumatoid arthritis; and prolonged overuse in the impingement position, e.g. in cleaning windows, which, when associated with a tendinopathy from age-related degenerative changes within the tendon, can lead to subsequent partial or complete tears of the cuff. Clinically, this condition causes tenderness over the anterior portion of the acromion, and pain which typically occurs on abducting the shoulder between 60° and 120° (the painful arc).

imageimageimage

imageimage

image_thumb8

The fibrous membrane of the joint capsule is thickened:

  • anterosuperiorly in three locations to form superior, middle, and inferior glenohumeral ligaments, which pass between the superomedial margin of the glenoid cavity to the lesser tubercle and inferiorly related anatomical neck of the humerus
  • superiorly between the base of the coracoid process and the greater tubercle of the humerus (the coracohumeral ligament);
  • between the greater and lesser tubercles of the humerus (transverse humeral ligament)-this holds the tendon of the long head of the biceps brachii muscle in the intertubercular sulcus

Rotator Interval (In Detail)

7. Rotator Interval  in detail :-The rotator cuff interval is a triangular space between the subscapularis and supraspinatus tendons and the base of the coracoid process, covered by the rotator interval capsule, whose main component is the coracohumeral ligament (CHL). The rotator cuff interval is a triangular space created by the intervention of the coracoid process between the subscapularis and supraspinatus muscles and tendons. The floor of the rotator cuff interval is the cartilage of the humeral head, and the roof of the rotator cuff interval is the rotator interval capsule, which links the subscapularis and supraspinatus tendons and is composed of two layers: the CHL on the bursal side and the fasciculus obliquus on the articular side.The rotator interval is an anatomic region in the anterosuperior aspect of the glenohumeral joint that represents a complex interaction of the fibers of the coracohumeral ligament, the superior glenohumeral ligament, the glenohumeral joint capsule, and the supraspinatus and subscapularis tendons. As basic science and clinical studies continue to elucidate the precise role of the rotator interval, understanding of and therapeutic interventions for rotator interval pathology also continue to evolve. Lesions of the rotator interval may result in glenohumeral joint contractures, shoulder instability, or in lesions to the long head of the biceps tendon. Long-term clinical trials may clarify the results of current surgical interventions and further enhance understanding of the rotator interval.

Rotator interval contents
• Coracohumeral ligament
• Superior glenohumeral ligament
• Long head biceps tendon

image

rt

The rotator cuff interval is a triangular space between the subscapularis and supraspinatus tendons and the base of the coracoid process, covered by the rotator interval capsule, whose main component is the coracohumeral ligament (CHL). The rotator cuff interval contains the long head of the biceps tendon (LBT) and the superior glenohumeral ligament (SGHL) [16]. The relationships between the CHL, the SGHL, and the LBT are complex and may be difficult to analyze on MRI because of the variable appearance of the CHL.

rt2

rl3

rl4

r5

r7

r8

8. Intermuscular Spaces:- Quadrangular space (from posterior) :-

 

image

image

Quadrangular space (from anterior):-

image

When viewed from anteriorly, its boundaries are formed by:

  • the inferior margin of the subscapularis muscle;
  • the surgical neck of the humerus;
  • the superior margin of the teres major muscle;
  • the lateral margin of the long head of the triceps brachii muscle

In the posterior scapular region, its boundaries are formed by:

  • the inferior margin of teres minor;
  • the surgical neck of the humerus;
  • the superior margin of teres major;
  • the lateral margin of the long head of triceps brachii.

9. Axillary nerve may be damaged by dislocation of shoulder or by the fracture neck of the humerus.Deltoid is paralyzed with loss of abduction at the shoulder.The rounded contour is lost leading to FLAT SHOULDER.There is sensory loss over lower half of the deltoid.

10.Anastomosis around the scapula:-

 

image

 

Deep branch of Transverse cervical artery makes anastomosis with suprascapular artery and circumflex scapular artery.This is an anastomosis between first part of subclavian artery and third part of axillary artery.

Q:- Subscapular artery is a branch of third part of axillary artery not sublclavian artery.Important Point

The thoraco-acromial artery is a short branch which arises from the second part of the axillary artery.

The suprascapular artery usually arises from the thyrocervical trunk of the subclavian artery, although it may arise from the third part of the subclavian artery

The lateral thoracic artery arises from the second part of the axillary artery

The superior thoracic artery is a small vessel which arises from the first part of the axillary artery near the lower border of subclavius.

image

 

The subscapular artery is the largest branch of the axillary artery. It usually arises from the third part of the axillary artery at the distal (inferior) border of subscapularis, which it follows to the inferior scapular angle, where it anastomoses with the lateral thoracic and intercostal arteries and the deep branch of the transverse cervical artery.

The other terminal branch of the subscapular artery, the thoracodorsal artery(DNB2010), follows the lateral margin of the scapula, posterior to the lateral thoracic artery, between latissimus dorsi and serratus anterior. Before entering the deep surface of latissimus dorsi, it supplies teres major and the intercostals and sends one or two branches to serratus anterior. It enters latissimus dorsi muscle with the thoracodorsal nerve: this constitutes the principle neurovascular pedicle to the muscle. It provides numerous musculocutaneous perforators which supply the skin over the superior part of latissimus dorsi. The intramuscular portion of the artery anastomoses with intercostal arteries and lumbar perforating arteries.

11. All the following are true about musculocutaneous nerve injury at shoulder except:  IMPORTANT Q
A.Loss of flexion at shoulder………ANS
B.Loss of flexion of forearm
C.Loss of supination of forearm
D.Loss of sensation on radial side of forearm

The main muscles producing flexion at shoulder are :- Pectoralis major clavicular head and Clavicular or anterior fibers of deltoid….IMP…Accesory muscle producing flexion at shoulder is Coracobrachialis supplied by Musculocutaneous nerve.

Flexion at forearm is lost as it supplies brachialis as well as Biceps brachii.

Supination is lost as Biceps brachii main action is supination when the forearm is flexed.(Supination is brought about by supinator and biceps brachii.Slow supination with elbow extended is done by supinator while rapid supination is done by biceps when arm is flexed against resistance.

Musculocutaneous nerve is injured at the lateral cord of brachial plexus, positive clinical findings would be
(A)Loss of flexion at shoulder
(B)Sensory loss on the radial side of the forearm….ANS
(C)Loss of extension of forearm
(D)Loss of extension of the wrist

The nerve involved in anterior dislocation of the shoulder is
A.Radial nerve
B.Axillary nerve
C.Ulnar nerve
D.Musculocutaneous nerve………ANS

Following anterior dislocation of the shoulder,a pt develops weakness of flexion at elbow and lack of sensation over the lateral aspect forearm; nerve injured is:
A.Radial nerve
B.Musculocutaneous nerve….ANS
C.Axillary nerve
D.Ulnar nerve

Interscalene approach to brachial plexus block does not provide optimal surgical anaesthesia in the area of distribution of which of the following nerve
A.Musculocutaneous
B.Ulnar……..ans
C.Radial
D.Median

Injury to radial nerve in lower part of spiral groove:
A.Spares nerve supply to extensor carpi radialis longus
B.Results in paralysis of anconeus muscle
C.Leaves extensions at elbow joint intact
D.Weakens pronation movement

An interscalene brachial plexus block relies on dispersion of the larger volume of local anesthetic within the interscalene groove to accomplish blockade of the brachial plexus.Each trunk divides onto an anterior and a posterior division behind the clavicle, at the apex of the axilla. Within the axilla, the divisions combine to produce the three cords, which are named lateral, medial, and posterior, according to their relationships to the axillary artery. From there on, individual nerves are formed as these neuronal elements descend distally.The interscalene approach to brachial plexus blockade results in consistent anesthesia of the shoulder, arm, and elbow. The interscalene block is not recommended for hand surgery; more distal approaches to the brachial plexus should be used instead (e.g., infraclavicular, axillary). T2 area is not anesthetized.(intercostobrachial nerve area is proper answer.In the above choices Ulnar nerve is the closest to the root values.

image

Miller says “Although this approach can be used for forearm and hand surgery, blockade of the inferior trunk (C8 through T1) is often incomplete and requires supplementation at the ulnar nerve for adequate surgical anesthesia in that distribution.”

Anatomy:-Between the scalene muscles, these nerve roots unite to form three trunks, which emerge from the interscalene space to lie cephaloposterior to the subclavian artery as it courses along the upper surface of the first rib. Therefore, the “superior” (C5 and C6), “middle” (C7), and “inferior” (C8 and T1) trunks are arranged accordingly and are not in a strict horizontal formation, as often depicted. At the lateral edge of the first rib, each trunk forms anterior and posterior divisions that pass posterior to the midportion of the clavicle to enter the axilla. Within the axilla, these divisions form the lateral, posterior, and medial cords, named for their relationship with the second part of the axillary artery.

12. Ligament of Struther`s:-Struther, ligament of: fibrous band (occasionally ossified) running between medial epicondyle and shaft of the humerus.

Struthers’ ligament is a ligament that extends between the shaft of the humerus and the medial epicondyle of the humerus.It is not a constant ligament and can be acquired or congenital. Its clinical significance arises form the fact that the median nerve, passes in the space between the ligament and the humerus, and in this space the nerve may be compressed leading to supracondylar process syndrome.The ligament is usually ignored and not mentioned due to the fact that its not always found.

Coracobrachialis is more important morphologically than functionally.It represent the medial compartment of the arm.In some animals the muscle is tricipital.In man the upper two heads have fused,but the musculocutaneous nerve passes between the remnants of these two heads.The third head (and the lowest) head of the muscle has  disappeared in man.Occasional persistence of the lower head is associated with the presence of the so called “ligament of struthers” which is a fibrous band extending from the suprocondylar process to the medial epicondyle of the humerus.Supracondylar process seen in 1%.The third head of the coracobrachialis is inserted into this ligament.The lower part of the pronator teres muscle takes origin from the same ligament.The median nerve,or the brachial artery,or both pass subjacent to the ligament.The ligament of struther is in fact a part of the tendon of the dorso-epitrochlearis which is related to the latissimus dorsi

struther

13.Musculocutaneous Nerve lies laterally to the Axillary Artery….IMPORTANT POINT.

image

image

14.

image

Musculocutaneous, median, and ulnar nerves in the arm.

The ulnar nerve enters the arm with the median nerve and axillary artery (Fig. 7.67). It passes through proximal regions medial to the axillary artery. In the middle of the arm, the ulnar nerve penetrates the medial intermuscular septum and enters the posterior compartment where it lies anterior to the medial head of the triceps brachii muscle. It passes posterior to the medial epicondyle of the humerus and then into the anterior compartment of the forearm.

The radial nerve originates from the posterior cord of the brachial plexus and enters the arm by crossing the inferior margin of the teres major muscle alongwith profunda brachii vessels in the lower triangular space ,the medial border of the space formed by the triceps and lateral border by humerus with apex down and base formed by the Teres Major above.  . As it enters the arm, it lies posterior to the brachial artery. Accompanied by the profunda brachii artery, the radial nerve enters the posterior compartment of the arm by passing through the triangular interval.As the radial nerve passes diagonally, from medial to lateral, through the posterior compartment, it lies in the radial groove directly on bone. On the lateral side of the arm, it passes anteriorly through the lateral intermuscular septum and enters the anterior compartment where it lies between the brachialis muscle and a muscle of the posterior compartment of the forearm-the brachioradialis muscle, which attaches to the lateral supraepicondylar ridge of the humerus. The radial nerve enters the forearm anterior to the lateral epicondyle of the humerus, just deep to the brachioradialis.The radial nerve at the elbow lies deep in a groove between brachialis and brachioradialis proximally and extensor carpi radialis distally. It divides into the superficial terminal branch and the posterior interosseous nerve just anterior to the lateral epicondyle

Radial nerve injury in the arm:-The radial nerve is tightly bound with the profunda brachii artery between the medial and lateral heads of the triceps brachii muscle in the radial groove. If the humerus is fractured the radial nerve may become stretched or transected in this region leading to permanent damage and loss of function. This injury is typical (Fig. 7.69) and the nerve should always be tested when a fracture of the midshaft of the humerus is suspected. The patient typically presents with wrist drop (due to denervation of the extensor muscles) and sensory changes over the dorsum of the hand.

In the arm and forearm the median nerve is usually not injured by trauma because of its relatively deep position. The commonest neurologic problem associated with the median nerve is compression beneath the flexor retinaculum at the wrist (carpal tunnel syndrome).

image

Muscle Origin Insertion Innervation Function
 
Brachioradialis Proximal part of lateral supraepicondylar ridge of humerus and adjacent inter-muscular septum Lateral surface of distal end of radius Radial nerve [C5,C6] before division into superficial and deep branches Accessory flexor of elbow joint when forearm is mid-pronated
 
Extensor carpi radialis longus Distal part of lateral supraepicondylar ridge of humerus and adjacent intermuscular septum Dorsal surface of base of metacarpal II Radial nerve [C6,C7] before division into superficial and deep branches Extends and abducts the wrist
 
Extensor carpi radialis brevis Lateral epicondyle of humerus and adjacent intermuscular septum Dorsal surface of base of metacarpals II and III Deep branch of radial nerve [C7,C8] before penetrating supinator muscle Extends and abducts the wrist
 
Extensor digitorum Lateral epicondyle of humerus and adjacent intermuscular septum and deep fascia Four tendons, which insert via ‘extensor hoods’ into the dorsal aspects of the bases of the middle and distal phalanges of the index, middle, ring, and little fingers Posterior interosseous nerve [C7,C8] Extends the index, middle, ring, and little fingers; can also extend the wrist
 
Extensor digiti minimi Lateral epicondyle of humerus and adjacent intermuscular septum together with extensor digitorum Dorsal hood of the little finger Posterior interosseous nerve [C7,C8] Extends the little finger
 
Extensor carpi ulnaris Lateral epicondyle of humerus and posterior border of ulna Tubercle on the base of the medial side of metacarpal V Posterior interosseous nerve [C7,C8] Extends and adducts the wrist
 
Anconeus Lateral epicondyle of humerus Olecranon and proximal posterior surface of ulna Radial nerve [C6 to C8] (via branch to medial head of triceps brachii) Abduction of the ulna in pronation; accessory extensor of the elbow joint

There is some variation in the level at which branches of the radial nerve arise from the main trunk in different subjects. Branches to extensor carpi radialis brevis and supinator may arise from the main trunk of the

radial nerve or from the proximal part of the posterior interosseous nerve, but almost invariably above the arcade of Frohse.

Arcade of Frohse, sometimes called the supinator arch is the most superior part of the superficial layer of the supinator muscle, and is a fibrous arch over the posterior interosseous nerve. The arcade of Frohse is the most frequent site of posterior interosseous nerve entrapment, and is believed to play a role in causing progressive paralysis of the posterior interosseous nerve, both with and without injury.

image

The deep branch of radial nerve may be damaged during an operation for exposure of the head of the radius.Since the extensor carpi radialis longus and brevis are spared wrist drop does not occur.

 A patient is brought to the emergency with history of trauma to his right upper limb. Extension of metacarpophalangeal is lost. There is no wrist drop and extension of IP joint is normal. The most likely nerve involved is :
(A)Ulnar nerve
(B)Median nerve
(C)
Radial nerve
(D)Posterior-interosseous nerve

Injury to radial nerve in lower part of spiral groove:
A.Spares nerve supply to extensor carpi radialis longus
B.Results in paralysis of anconeus muscle
C.Leaves extensions at elbow joint intact
D.Weakens pronation movement

One of the branches to the medial head of the triceps brachii muscle arises before the radial nerve’s entrance into the posterior compartment and passes vertically down the arm in association with the ulnar nerve

Damage to the radial nerve in the spinal groove spares which muscle
A.Lateral head of triceps
B.Long head of triceps
C.Medial head of triceps
D.Anconeus

Controversial Question

Injury to radial nerve in lower part of spiral groove:
A.Spares nerve supply to extensor carpi radialis longus— True
B.Results in paralysis of anconeus muscle—false Upper part of groove branch is given
C.Leaves extensions at elbow joint intact—-False  Weakens
D.Weakens pronation movement—-false Median nerve supplies pronators

image

RADIAL NERVE (see above diagram) :-The radial nerve descends behind the third part of the axillary artery and the upper part of the brachial artery, anterior to subscapularis and the tendons of latissimus dorsi and teres major. With the profunda brachii artery it inclines dorsally, passing through the triangular space below the lower border of teres major, between the long head of triceps and the humerus. Here it supplies the long head of triceps, and gives rise to the posterior cutaneous nerve of the arm (not forearm)which supplies the skin along the posterior surface of the upper arm. It then spirals obliquely across the back of the humerus, lying posterior to the uppermost fibres of the medial head of triceps which separate the nerve from the bone in the first part of the spiral groove. Here it gives off a muscular branch to the lateral head of triceps and a branch which passes through the medial head of triceps to anconeus. On reaching the lateral side of the humerus it pierces the lateral intermuscular septum to enter the anterior compartment; it then descends deep in a furrow between brachialis and proximally brachioradialis, then more distally extensor carpi radialis longus. Anterior to the lateral epicondyle it divides into superficial and deep terminal rami.

The branches of the radial nerve in the upper arm are: muscular, cutaneous, articular and superficial terminal and posterior interosseous.

Muscular branches :-Muscular branches supply triceps, anconeus, brachioradialis, extensor carpi radialis longus and brachialis in medial, posterior and lateral groups. Medial muscular branches arise from the radial nerve on the medial side of the arm. They supply the medial and long heads of triceps; the branch to the medial head is a long, slender filament which, lying close to the ulnar nerve as far as the distal third of the arm, is often termed the ulnar collateral nerve. A large posterior muscular branch arises from the nerve as it lies in the humeral groove. It divides to supply the medial and lateral heads of triceps and anconeus, that for the latter being a long nerve which descends in the medial head of triceps and partially supplies it; it is accompanied by the middle collateral branch of the profunda brachii artery and passes behind the elbow joint to end in anconeus. Lateral muscular branches arise in front of the lateral intermuscular septum; they supply the lateral part of brachialis, brachioradialis and extensor carpi radialis longus.

 

Untitled

15. Pronator teres in addition to the main pronator of forearm also causes flexion at elbow joint.

16.”D”eep muscles of the front of forearm (Flexor digitorum  Profundus & Flexor pollicis longus)  acts on the “D”istal IP joint.

17. Flexor digitorum superficialis acts on the Proximal IP joint.

18.Flexor “carpi” radialis:- Flexes the wrist and abductor of the wrist.RADIALIS(RADIUS)=LATERAL..so acts laterally.Carpi—so acts on wrist.

Palmaris Longus:- Absent in 10% of subjects.

Flexor carpi ulnaris:-Flexes and adduct the wrist.Ulnaris—so adduct.Carpi –so flexes the wrist.

All muscles except the flexor carpi ulnaris in the forearm are supplied by the median nerve.

The pisiform bone is a seasmoid bone in the tendon of Flexor carpi ulnaris.

19.The Cubital Fossa:-The cubital fossa is an important area of transition between the arm and the forearm. It is located anterior to the elbow joint and is a triangular depression formed between two forearm muscles:

  • the brachioradialis muscle originating from the lateral supraepicondylar ridge of the humerus;
  • the pronator teres muscle originating from the medial epicondyle of the humerus image

image

20. Ape thumb Deformity:-   Injury of median nerve at wrist leads to wasting of thenar muscles and the thumb is adducted and laterally rotated.:- ABDUCTION IS LOST,OPPOSITION IS LOST,FLEXION IS LOST.Ape hand deformity is a deformity in humans who cannot move the thumb outside of the plane of the palm. It is caused by inability to oppose the thumb and the limited abduction of the thumb.

Apehand_1

              Ape Hand Deformity

image

image

Flexion and extension should be confined to motion at the interphalangeal or metacarpophalangeal joints (Fig. 53.49A-C). Palmar abduction (Fig. 53.49D, E), in which the first metacarpal moves away from the second at right angles to the plane of the palm, and radial abduction (Fig. 53.49D, F), in which the first metacarpal moves away from the second with the thumb in the plane of the palm, occur at the carpometacarpal joint. The opposite of radial abduction is ulnar adduction, or transpalmar adduction, in which the thumb crosses the palm towards its ulnar border. In clinical practice the term adduction is generally used without qualification. Circumduction describes the angular motion of the first metacarpal, solely at the carpometacarpal joint, from a position of maximal radial abduction in the plane of the palm towards the ulnar border of the hand, maintaining the widest possible angle between the first and second metacarpals (Fig. 53.49G). Lateral inclinations of the first phalanx maximize the extent of excursion of the circumduction arc. Opposition is a composite position of the thumb achieved by circumduction of the first metacarpal, internal rotation of the thumb ray and maximal extension of the metacarpophalangeal and interphalangeal joints (Fig. 53.49H). Retroposition is the opposite to opposition (Fig. 53.49I). Flexion adduction is the position of maximal transpalmar adduction of the first metacarpal: the metacarpophalangeal and interphalangeal joints are flexed and the thumb is in contact with the palm (Fig. 53.49J).

21.

image

Most branches to the muscles in the superficial and intermediate layers of the forearm originate medially from the nerve just distal to the elbow joint:

  • The largest branch of the median nerve in the forearm is the anterior interosseous nerve, which originates between the two heads of pronator teres, passes distally down the forearm with the anterior interosseous artery, innervates the muscles in the deep layer (flexor pollicis longus, the lateral half of flexor digitorum profundus, and pronator quadratus) and terminates as articular branches to joints of the distal forearm and wrist.
  • A small palmar branch originates from the median nerve in the distal forearm immediately proximal to the flexor retinaculum , passes superficially into the hand and innervates the skin over the base and central palm. This palmar branch is spared in carpal tunnel syndrome because it passes into the hand superficial to the flexor retinaculum of the wrist.
    Since the terminal phalanges of little and ring fingers are supplied by ulnar nerve(Ulnar nerve supplies the medial half of digital profundus muscle) These Fingers DIP are spared in Median nerve injury.

Also the PIP joint of thumb is spared as flexor pollicis brevis deep supplied by ulnar nerve.

There is one IP joint  in the thumb and MCP joint.Flexor pollicis brevis causes flexion at MCP jt. and Flexor pollicis longus causes flexion at IP joint of thumb.Both supplied by Median nerve.

So thumb is adducted(abduction is lost due to abductor pollicis brevis paralysisi) and laterally rotated 9as medial rotation by the opponens pollicis is lost.)

Flexor pollicis brevis :The flexor pollicis brevis muscle is distal to abductor pollicis brevis.It originates mainly from the tubercle of the trapezium and adjacent flexor retinaculum, but it may also have deeper attachments to other carpal bones and associated ligaments. It inserts into the lateral side of the base of the proximal phalanx of the thumb. The tendon often contains a sesamoid bone(DNB 2010).Flexor pollicis brevis flexes the metacarpophalangeal joint of the thumb.

image

22. Extensor Hoods:-

image

The tendons of the extensor digitorum and extensor pollicis longus muscles pass onto the dorsal aspect of the digits and expand over the proximal phalanges to form complex ‘extensor hoods‘ or ‘dorsal digital expansions‘ .

Because force from the small intrinsic muscles of the hand is applied to the extensor hood distal to the fulcrum of the metacarpophalangeal joints, the muscles flex these joints .Simultaneously, the force is transferred dorsally through the hood to extend the interphalangeal joints. This ability to flex the metacarpophalangeal joints, while at the same time extending the interphalangeal joints, is entirely due to the intrinsic muscles of the hand working through the extensor hoods. This type of precision movement is used in the ‘upstroke’ when writing a ‘t’.

In the index, middle, ring, and little fingers, the lumbrical, interossei, and abductor digiti minimi muscles attach to the extensor hoods. In the thumb, the adductor pollicis and abductor pollicis brevis muscles insert into and anchor the extensor hood.

Q:-The lumbricals muscles extend the MCP joints and extend the IP joints of the digit in which they insert.

23. Anatomical Snuff Box:-

Regarding the anatomical snuff box which of the following is true:
(A)Abductor Pollicis longus forms the posterior wall. (it forms the anterior wall)
(B)Abductor pollicis longus and Extensor pollicis brevis form the anterior wall. ….ans
(C)Basilus vein forms the roof.            (its cephalic not basilic)
(D)Floor is formed by Extensor carpi radialis longus and brevis.??

Basilic vein is on the ulnar side not on the radial side-Remember

image

The ‘anatomical snuffbox’ is a term given to the triangular depression formed on the posterolateral side of the wrist and metacarpal I by the extensor tendons passing into the thumb . Historically, ground tobacco (snuff) was placed in this depression before being inhaled into the nose. The base of the triangle is at the wrist and the apex is directed into the thumb. The impression is most apparent when the thumb is extended:

  • the lateral border is formed by the tendons of the abductor pollicis longus and extensor pollicis brevis;
  • the medial border is formed by the tendon of the extensor pollicis longus;
  • the floor of the impression is formed by the scaphoid and trapezium, and distal ends of the tendons of the extensor carpi radialis longus and extensor carpi radialis brevis.

The radial artery passes obliquely through the anatomical snuffbox, deep to the extensor tendons of the thumb and lies adjacent to the scaphoid and trapezium.

Terminal parts of the superficial branch of the radial nerve pass subcutaneously over the snuffbox as does the origin of the cephalic vein from the dorsal venous arch of the hand.

image

After passing around Lister’s tubercle, the tendon of extensor pollicis longus crosses the tendons of extensor carpi radialis brevis and longus obliquely .When the thumb is fully extended the tendon is separated from extensor pollicis brevis by a triangular depression or fossa, the so-called ‘anatomical snuff-box’. Bony structures can be felt in the floor of this fossa by deep palpation. In proximal to distal order they are the radial styloid, the smooth convex articular surface of the scaphoid, the trapezium, and the base of the first metacarpal. The latter are more easily felt during metacarpal movement, while the scaphoid is more easily felt during adduction and abduction of the hand

The tendon of extensor pollicis brevis can be felt at the radial border of the anatomical snuff-box, lying medial to the tendon of abductor pollicis longus, when the metacarpophalangeal joint of the thumb is extended against resistance

The tendon of extensor pollicis longus can be palpated at the ulnar border of the anatomical snuff-box when the thumb is extended at the interphalangeal joint against resistance.

MOST IMP POINT:- ABDUCTOR POLLICIS LONGUS LIES IN THE POST COPARTMENT OF FOREARM/WRIST.

ABDUCTOR POLLICIS BREVIS IS A THENAR MUSCLE.

SO NERVE SUPPLY OF FORMER IS RADIAL NERVE WHILE NERVE SUPPLY OF LATER IS MEDIAN NERVE.

24.The carpal tunnel contains all of the following important structures except:
A.Median Nerve.
B.Flexor pollicis longus.
C.
Flexor carpi radialis.
D.Flexor digitorum superficialis.

 

image

The structures passing superficial to the flexor retinaculum are:- a)the tendon of the palmaris longus b)the palmar cutaneous branch of the median nerve c)the palmar cutaneous branch of the ulnar nerve d)the ulnar vessels e) the ulnar nerve.

The ulnar artery, ulnar nerve, and tendon of palmaris longus pass into the hand anterior to the flexor retinaculum and therefore do not pass through the carpal tunnel .

The four tendons of the flexor digitorum profundus, the four tendons of the flexor digitorum superficialis, and the tendon of the flexor pollicis longus pass through the carpal tunnel, as does the median nerve,Others are radial bursa and ulnar bursa

All the tendons of the flexor digitorum profundus and flexor digitorum superficialis are surrounded by a single synovial sheath; a separate sheath surrounds the tendon of the flexor pollicis longus. The median nerve is anterior to the tendons in the carpal tunnel.

The tendon of flexor carpi radialis is surrounded by a synovial sheath and passes through a tubular compartment formed by the attachment of the lateral aspect of the flexor retinaculum to the margins of a groove on the medial side of the tubercle of trapezium.It lies between the retinaculum and its deep slip,in the grrove on the trapezium.

25. Ofcourse the lumbricals do not insert into the thumb as polllicis has its own separate  thenar muscles.

So 1st lumbricals insert into 2nd MCP joint and so-on so that the 4th lumbrical inserted into the 5th MCP joint..

So 1st lumbicals acts on the index finger but not the thumb or 1st MCP joint,,,imp.They arise from the tendon of the Flexor digitorum profundus (as FLEX DIGITORUM PROFUNDUS is obviously inserted into the 2nd to 5th digits)and inserted into the DDE(dorsal digital expansion of Extensor digitorum.

26.Palmar interossei are abductors while Dorsal interossei are adductors of the fingers

27. All Interossei and lumbricals Flex the MCP and Extend the IP joint.

28.Midpalmar Space:-Laterally by the intermediate palmar septum attaching the palmar aponeurosis to the third metacarpal bone.

Medially by the the medial palmar septum.

29.

image

The radial artery curves around the lateral side of the wrist, passes over the floor of the anatomical snuffbox and into the deep plane of the palm by penetrating anteriorly through the back of the hand . It passes between the two heads of the first dorsal interosseous muscle and then between the two heads of the adductor pollicis to access the deep plane of the palm and form the deep palmar arch.

Allen’s test:-To test for adequate anastomoses between the radial and ulnar arteries, compress both the radial and ulnar arteries at the wrist, then release pressure from one or the other, and determine the filling pattern of the hand. If there is little connection between the deep and superficial palmar arteries only the thumb and lateral side of the index finger will fill with blood (become red) when pressure on the radial artery alone is released

The deep palmar arch passes medially through the palm between the metacarpal bones and the long flexor tendons of the digits. On the medial side of the palm, it communicates with the deep palmar branch of the ulnar artery .

ANCONEUS

Anconeus is a small, triangular muscle posterior to the elbow joint and is partially blended with triceps (Figs 52.15, 52.17). Anconeus arises by a separate tendon from the posterior surface of the lateral epicondyle of the humerus. Its fibres diverge medially towards the ulna, covering the posterior aspect of the annular ligament, and are attached to the lateral aspect of the olecranon and proximal quarter of the posterior surface of the shaft of the ulna.

imageimage

The extent to which anconeus fuses with triceps or extensor carpi ulnaris is variable

 

Anconeus assists triceps in extending the elbow joint. Its major function is not clear, but it may be the control of ulnar abduction in pronation, which is necessary if the forearm is to turn over the hand without translating it medially. In this way a tool can be revolved ‘on the spot’ or it can be swept through an arc.Anconeus abducts the ulna during pronation to maintain the center of the palm over the same point when the hand is flipped.

                        JOINTS

Which is true about synovial joint ? :
(A)Stability is inversely proportional to mobility.FALSE*(The mechanical function of the synovial joints is to permit motion whilst carrying functional loads and remaining stable)
(B)Hyaline cartilage covers articular surface of all synovial joints.TRUE—MOSTLY
(C) Metacarpo-phalangeal joint is a hinge joint. FALSE IT IS CONDYLOID
(D)”Cartilage usually divides the joint into two cavities”FALSE-ARTICULAR DISC DIVIDES.

image

A and B are purely diagrammatic and not related to particular joints. C, however, is a simplified representation of some features of an elbow joint but the complicated contours due to the olecranon, coronoid and radial fossae and profiles of articular fat pads present in a true section have been omitted.

Articular surfaces are mostly formed by a special variety of hyaline cartilage, reflecting their preformation as parts of cartilaginous models in embryonic life. Exceptionally, surfaces of the sternoclavicular and acromioclavicular joints and both temporomandibular surfaces are covered by dense fibrous tissue which contains isolated groups of chondrocytes and little surrounding matrix – a legacy of their formation by intramembranous ossification. Articular cartilage has a wear-resistant, low-frictional, lubricated surface, which is slightly compressible and elastic and is thus ideally constructed for easy movement over a similar surface. It is also able to absorb large forces of compression and shear generated by gravity and muscular power.

A fibrous capsule completely encloses a joint except where it is interrupted by synovial protrusions; the exceptions are described with the individual joints. The capsule is composed of parallel but interlacing bundles of white collagen fibres which form a cuff whose ends are attached continuously round the articular ends of the bones concerned.

An articular disc or meniscus occurs between articular surfaces where congruity is low. It consists of fibrocartilage, where the fibrous element is usually predominant, and is not covered by synovial membrane. A disc may extend across a synovial joint, dividing it structurally and functionally into two synovial cavities. Discs are connected at their periphery to fibrous capsules, usually by vascularized connective tissue, so that they become invaded by vessels and afferent and motor (sympathetic) nerves; sometimes the union is closer and stronger, as in the knee and temporomandibular joints. Their main part contains few cells, but their surfaces may be covered by an incomplete stratum of flat cells, continuous at the periphery with adjacent synovial membrane

Synovial Joints Joint capsule containing synovial membrane and
synovial fluid
1. Gliding Flattened or slightly curved articulating surfaces Sliding Intercarpal and intertarsal joints
2. Hinge Concave surface of one bone articulates with Bending motion in one plane Knee; elbow; joints of phalanges
convex surface of another
3. Pivot Conical surface of one bone articulates with Rotation about a central axis Atlantoaxial joint; proximal
depression of another radioulnar joint
4. Condyloid Oval condyle of one bone articulates with Movement in two planes Radiocarpal joint;
elliptical cavity of another metacarpophalangeal joint
5. Saddle Concave and convex surface on each Wide range of movements Carpometacarpal joint of thumb
articulating bone
6. Ball-and-socket Rounded convex surface of one bone articulates Movement in all planes and Shoulder and hip joints
with cuplike socket of another rotation

imageimageimageimage

           Saddle joint-CARPOMETACARPAL                                                   BALL & SOCKET                                                                    HINGE                                                  CONDYLOID(ELLIPSOID)-MCP

imageimage

                            PIVOT  atlas with the axis                                                                        GLIDING-intercarpal

Ellipsoid joints:- Ellipsoid joints are biaxial, and consist of an oval, convex surface apposed to an elliptical concavity, e.g. radiocarpal and metacarpophalangeal joints. Primary movements are about two orthogonal axes, e.g. flexion-extension, abduction-adduction, which may be combined as circumduction; rotation around the third axis is largely prevented by general articular shape.

Plane joints(GLIDING) :- Plane joints are appositions of almost flat surfaces (e.g. intermetatarsal and some intercarpal joints). Slight curvature is usual, although often disregarded, and movements are considered to be pure translations or sliding between bones. However, in precise dynamics even slight curvatures cannot be ignored

Ginglymi (hinge) joints:- Ginglymi resemble hinges and restrict movement to one plane, i.e. they are uniaxial. They have strong collateral ligaments to aid this, e.g. interphalangeal and humero-ulnar joints. The surfaces of such biological hinges differ from regular mechanical cylinders in that their profiles are not arcs but varyingly spiral, and therefore motion is not truly about a single axis.

Posted in Medical | Tagged: , , , | 11 Comments »

Anatomy Notes Vol.1 with Orthopaedics

Posted by Dr KAMAL DEEP on December 17, 2010

Note:-Bolded or underlined statements are previous questions.

1.Attachments on the scapula:-No attachments for Pectoralis Major.

imageimage

image

image

2.SITminor(Supraspinatus,Infraspinatus,Teres Minor inserted on gretaer tubercle of humerus on posterior side of top of humerus. All have attachments on scapula.Subscapularis inserted on Lesser tubercle of humerus.Pectoralis minor is inserted on coracoid process.

3.Tip of coracoid process:- Short Head of biceps and Coracobrachialis.

4.Carpal Bones :-

image

Proximal row:- ScaLunaTriqPisi (Scaphoid Lunate Triquetral Pisiform):Lateral to medial

Distal Row :- Trapezium,Trapezoid,Capitate and Hamate: Lateral to medial

The pisiform is a sesamoid bone in the tendon of flexor carpi ulnaris and articulates with the anterior surface of the triquetrum.

Most common site of scaphoid fracture is :
(A)Waist
(B)Proximal fragment
(C)Distal fragment
(D)Tilting of the lunate

Fractures of the scaphoid are the most common of carpal fractures. They usually occur in young adult men following falls on their outstretched palms. Experimental studies have shown that the force must be applied to the radial side of the palm, with the wrist extended a minimum of 95° (102). In that position, the scaphoid is the only carpal bone in contact with the radius. The proximal part of the scaphoid assumes a wedge-shaped configuration between the radius and capitate, where it is supported by the radial collateral and radiocapitate ligaments. The distal pole of the scaphoid, however, is unsupported and capsular structures in the area are lax. It is the distal pole that receives most of the applied force and the bone fractures at its most vulnerable area, its waist.

The profile of the bone is best seen on PA and posterior-oblique views with the wrist in ulnar deviation ( The posterior-oblique view visualizes the carpal bones on the radial side of the wrist, particularly the scaphoid, and the anterior-oblique view visualizes the pisiform and, to a lesser extent, the hamate)

Although radiographs taken immediately after the injury may be negative, the scaphoid should still be considered fractured until proven otherwise. Immobilize the wrist in a thumb spica splint or cast and repeat radiographs in 1 to 2 weeks. If there is a fracture, it should then be evident by the appearance of bone resorption at the fracture site. Occasionally, bone resorption does not appear until 3 weeks after the fracture, and even then radiographs may remain inconclusive. In these cases, radionuclide imaging with technetium-99m (99mTc) can be helpful (32). Although bone scans are highly sensitive and are generally positive within 24 h of a fracture, they are nonspecific. Therefore, although a fracture can be ruled out with a negative scan, a positive scan requires more specific imaging studies. Vibratory testing, using audible “intrasound” frequencies between 20 and 20,000 Hz (infrasound less than 20 Hz and ultrasound greater than 20,000 Hz are inaudible), has been shown to be effective in diagnosing occult scaphoid fractures (8). The test is considered positive when pain is sufficient to cause an immediate “positive retraction response.” The definitive test is a CT scan.

The second method of classification is based on the site of the fracture within the scaphoid, which is separated into proximal, middle, and distal thirds. Most fractures involve the middle third of the bone. They usually heal if they are not displaced, and there is no intercarpal instability.Q:- Fractures in the proximal third, sometimes referred to as the proximal pole of the scaphoid, have the highest incidence of nonunion and avascular necrosis because of the pattern of intraosseous circulation. The blood supply to the scaphoid enters dorsally and distally and traverses the bone in a proximal direction (36). Fractures in the distal third of the scaphoid are the rarest and tend to heal promptly because of the excellent blood supply in the area. Distal-third fractures include intraarticular fractures and fractures of the tubercle.

Q:-So non-union and delayed union is more common than malunion.

Avascular necrosis of the scaphoid (Priser’s disease) and of the lunate (Kienbock’s disease).

5.The anterior group of lymph nodes lie along the lateral thoracic vessels.Approximately 75% is via lymphatic vessels that drain laterally and superiorly into axillary nodes.

As indicated in Fig. 17-8, the lymph node groups are assigned levels according to their anatomic relationship to the pectoralis minor muscle(not pectoralis major). Lymph nodes located lateral to or below the lower border of the pectoralis minor muscle are referred to as level I lymph nodes, which include the axillary vein, external mammary(anterior axillary or pectoral group), and scapular groups. Lymph nodes located superficial or deep to the pectoralis minor muscle are referred to as level II lymph nodes, which include the central and interpectoral groups. Lymph nodes located medial to or above the upper border of the pectoralis minor muscle are referred to as level III lymph nodes, which consist of the subclavicular group. The plexus of lymph vessels in the breast arises in the interlobular connective tissue and in the walls of the lactiferous ducts and communicates with the subareolar plexus of lymph vessels. Efferent lymph vessels from the breast pass around the lateral edge of the pectoralis major muscle and pierce the clavipectoral fascia, ending in the external mammary (anterior, pectoral) group of lymph nodes. Some lymph vessels may travel directly to the subscapular (posterior, scapular) group of lymph nodes. From the upper part of the breast, a few lymph vessels pass directly to the subclavicular (apical) group of lymph nodes. The axillary lymph nodes usually receive >75% of the lymph drainage from the breast. The rest is derived primarily from the medial aspect of the breast, flows through the lymph vessels that accompany the perforating branches of the internal mammary artery, and enters the parasternal (internal mammary) group of lymph nodes

clip_image002

Axillary lymph node groups. Level I includes lymph nodes located lateral to the pectoralis minor muscle (PM); level II includes lymph nodes located deep to the PM; and level III includes lymph nodes located medial to the PM. Arrows indicate the direction of lymph flow. The axillary vein with its major tributaries and the supraclavicular lymph node group are also illustrated.

The boundaries for lymph drainage of the axilla are not well demarcated, and there is considerable variation in the position of the axillary lymph nodes. The six axillary lymph node groups recognized by surgeons (Figs. 17-7 and 17-8) are (a) the axillary vein group (lateral), which consists of four to six lymph nodes that lie medial or posterior to the vein and receive most of the lymph drainage from the upper extremity; (b) the external mammary group (anterior or pectoral group), which consists of five or six lymph nodes that lie along the lower border of the pectoralis minor muscle contiguous with the lateral thoracic vessels and receive most of the lymph drainage from the lateral aspect of the breast; (c) the scapular group (posterior or subscapular), which consists of five to seven lymph nodes that lie along the posterior wall of the axilla at the lateral border of the scapula contiguous with the subscapular vessels and receive lymph drainage principally from the lower posterior neck, the posterior trunk, and the posterior shoulder; (d) the central group, which consists of three or four sets of lymph nodes that are embedded in the fat of the axilla lying immediately posterior to the pectoralis minor muscle and receive lymph drainage both from the axillary vein, external mammary, and scapular groups of lymph nodes, and directly from the breast; (e) the subclavicular group (apical), which consists of six to twelve sets of lymph nodes that lie posterior and superior to the upper border of the pectoralis minor muscle and receive lymph drainage from all of the other groups of axillary lymph nodes; and (f) the interpectoral group (Rotter’s nodes), which consists of one to four lymph nodes that are interposed between the pectoralis major and pectoralis minor muscles and receive lymph drainage directly from the breast. The lymph fluid that passes through the interpectoral group of lymph nodes passes directly into the central and subclavicular groups.

clip_image004

6. Clavipectoral Fascia:-

image

Pierced by LTC

L-Lateral pectoral nerve

T-Thoracoacromial vessels

C—Cephalic VEIN

Clavipectoral fascia:-The clavipectoral fascia is a strong fibrous sheet behind the clavicular part of pectoralis major. It fills the gap between pectoralis minor and subclavius, and covers the axillary vessels and nerves. It splits around subclavius and is attached to the clavicle both anterior and posterior to the groove for subclavius. The posterior layer fuses with the deep cervical fascia which connects omohyoid to the clavicle and with the sheath of the axillary vessels. Medially it blends with the fascia over the first two intercostal spaces and is attached to the first rib, medial to subclavius. Laterally, it is thick and dense, and is attached to the coracoid process, blending with the coracoclavicular ligament. Between the first rib and coracoid process the fascia often thickens to form a band, the costocoracoid ligament. Below this the fascia becomes thin, splits around pectoralis minor and descends to blend with the axillary fascia and laterally with the fascia over the short head of biceps. The cephalic vein, thoraco-acromial artery and vein, and lateral pectoral nerve pass through the fascia.

7. Serratus Anterior muscle :- SERRATUS (AT = 8 Digitations from upper eight ribs)

Nerve supply:- C5,C6 and C7(long thoracic nerve)

Also called as Boxer`s muscle.-Along with the pectoralis minor the muscle pulls the scapula forwards around the chest wall to protract the upper limb(in pushing and punching movements)

Forms the Medial Wall of Axilla

Damage to the long thoracic nerve;-Because the long thoracic nerve passes down the lateral thoracic wall on the external surface of the serratus anterior muscle, just deep to skin and subcutaneous fascia, it is vulnerable to damage. Loss of function of this muscle causes the medial border, and particularly the inferior angle, of the scapula to elevate away from the thoracic wall, resulting in characteristic ‘winging’ of the scapula, on pushing forward with the arm.

True bout the Serratus anterior muscle is
A. Originates from the lower four ribs (upper 8 ribs)
B. Bipennate muscle (8 pinna)
C. Supplied by the subscapular nerve  (long thoracic nerve C5 C6 C7 roots)
D/ Helps in forced inspiration –True

Winging of scapula is due to paralysis of :
(A) Rhomboides (B) Trapezius
(C) L. dorsi (D) Serratus-anterior

8. Axilla:- The axillary inlet is oriented in the horizontal plane and is somewhat triangular in shape, with its apex directed laterally.The margins of the inlet are completely formed by bone.

  • the medial margin is the lateral border of rib I;
  • the anterior margin is the posterior surface of the clavicle;
  • the posterior margin is the superior border of the scapula The apex of the triangularly shaped axillary inlet is lateral in position and is formed by the medial aspect of the coracoid process
  • imageimage

The anterior wall is formed by pectorales major and minor, the former covering the whole wall, the latter its intermediate part. The interval between the upper border of pectoralis minor and clavicle is occupied by the clavipectoral fascia. The posterior wall is formed by subscapularis above, and teres major and latissimus dorsi below. The medial ‘wall’ is convex laterally and is composed of the first four ribs and their associated intercostal muscles, together with the upper part of serratus anterior. The anterior and posterior walls converge laterally: the ‘wall’ is narrow and consists of the humeral intertuberous sulcus. The lateral angle lodges coracobrachialis and biceps.

So lateral wall is very narrow,its actually an angle.

Contents of Axilla:-

The axilla contains the axillary vessels, the infraclavicular part of the brachial plexus and its branches, lateral branches of some intercostal nerves, many lymph nodes and vessels, loose adipose areolar tissue and, in many instances, the ‘axillary tail’ of the breast. The axillary vessels and brachial plexus run from the apex to the base along the lateral wall, nearer to the anterior wall: the axillary vein is anteromedial to the artery. The obliquity of the upper ribs means that the neurovascular bundle, after it emerges from behind the clavicle, crosses the first intercostal space: its relations are therefore different at upper and lower levels. Thoracic branches of the axillary artery are in contact with the pectoral muscles; the lateral thoracic artery reaches the thoracic wall along the lateral margin of pectoralis minor. q:-Subscapular vessels descend on the posterior wall at the lower margin of subscapularis. The subscapular and thoracodorsal nerves cross the anterior surface of latissimus dorsi at different inclinations. Circumflex scapular vessels wind round the lateral border of the scapula; posterior circumflex humeral vessels and the axillary nerve curve back and laterally around the surgical neck of the humerus.

No large vessel lies on the medial ‘wall’, which is crossed proximally only by small branches of the superior thoracic artery. The long thoracic nerve descends on serratus anterior and the intercostobrachial nerve perforates the upper anterior part of this wall, crossing the axilla to its lateral ‘wall’

9.The Brachial Plexus:-Branches of the brachial plexus may be described as supraclavicular and infraclavicular

From roots 1. Nerves to scaleni and longus colli C5, 6, 7, 8
  2. Branch to phrenic nerve C5
  3. Dorsal scapular nerve C5
  4. Long thoracic nerve C5, 6 (7)
From trunks 1. Nerve to subclavius C5, 6
  2. Suprascapular nerve C5, 6

Dorsal Scapular nerve supplies rhomboids

Long thoracic nerve supplies the serratus anterior.

Point to note nerves from roots supplies the muscles inserted into the medial margin of Scapula.

The lateral pectoral nerve is larger than the medial, and may arise from the anterior divisions of the upper and middle trunks, or by a single root from the lateral cord. Its axons are from the fifth to seventh cervical rami. It crosses anterior to the axillary artery and vein, pierces the clavipectoral fascia and supplies the deep surface of pectoralis major. It sends a branch to the medial pectoral nerve, forming a loop in front of the first part of the axillary artery  to supply some fibres to pectoralis minor.

In a postfixed plexus the contribution by T1 is large,T2 is always present,C4 is absent and C5 is reduced in size.

In a prefixed plexus the contribution by C4 is large and that from T2 is absent,

Lower subscapular nerve supplies teres major

Upper and Lower subscapular Nerve supplies Subscapular muscles.

ROOT VALUES :-a) Musculocutaneous nerve:-C5,C6,C7 (Branches of lateral cord)

b)Ulnar Nerve :- C7C8T1 (Medial Cord)

c) Axillary nerve :- C5C6 (POST CORD)

D) Radial nerve (c5,c6,c7,c8,t1) Post Cord

10. Erbs Paralysis:- Upper Trunk C5,C6 injury   CAUSES Policemans tip or Porters Tip hand.Arm HANGS BY SIDE,IT IS ADDUCTED AND MEDIALLY ROTATED.Supination as well as flexion is lost ,so is abduction.

11.Klumpkes Paralysis/Neurogenic Thoracic Outlet Syndrome (arterial type is also discussed in addition due to anatomic relevance) :- Lower trunk (C8T1) injury causes Claw Hand due to unapposed action of long flexors and extensors of the fingers.In a claw hand there is hyperextension at the MCP joint and flexion at the IP joints.Horners syndrome is also seen in Klumpke`s paralysis.Klumpke`s paralysis is seen in Thoracic Outlet syndrome.Thoracic outlet is an anatomic region containing First Rib,Subclavian Artery and vein Brachial Plexus,The clavicle and Lung Apex.

image

image

At the superior thoracic aperture(Thoracic Outlet) , the superior aspects of the pleural cavities, which surround the lungs, lie on either side of the entrance to the mediastinum .Structures that pass between the upper limb and thorax pass over rib I and the superior part of the pleural cavity as they enter and leave the mediastinum. Structures that pass between the neck and head and the thorax pass more vertically through the superior thoracic aperture.

True neurogenic thoracic outlet syndrome (TOS) results from compression of the lower trunk of the brachial plexus or ventral rami of the C8 or T1 nerve roots by an anomalous band of tissue connecting an elongate transverse process at C7 with the first RIB.

Patients with neurogenic thoracic outlet compression may develop shoulder and arm pain, weakness, and paresthesias. Patients with arterial compression may experience claudication, Raynaud’s phenomenon, and even ischemic tissue loss and gangrene. Venous compression may cause thrombosis of the subclavian and axillary veins; this is often associated with effort and referred to as Paget-Schroetter syndrome.(New in 17th ed Harrison Page 1571)

Adson’s test is used to assess for the presence of Thoracic Outlet Syndrome at the scalene triangle. The patient is examined standing. The examiner palpates the radial pulse while moving the upper extremity in abduction, extension, and external rotation. The patient then is asked to rotate her head toward the involved side while taking a deep breath and holding it. A positive exam will result in a diminished or absent radial pulse.

Several maneuvers that support the diagnosis of thoracic outlet compression syndrome may be used to precipitate symptoms, cause a subclavian artery bruit, and diminish arm pulses. These include the abduction and external rotation test, in which the affected arm is abducted by 90° and the shoulder is externally rotated; the scalene maneuver (extension of the neck and rotation of the head to the side of the symptoms); the costoclavicular maneuver (posterior rotation of shoulders); and the hyperabduction maneuver (raising the arm 180°).Most patients can be managed conservatively. They should be advised to avoid the positions that cause symptoms. Many patients benefit from shoulder girdle exercises. Surgical procedures such as removal of the first rib or resection of the scalenus anticus muscle are necessary occasionally for relief of symptoms or treatment of ischemia.

12.  Trapezius (Accessory Nerve,XI):- Each trapezius muscle is flat and triangularly shaped, with the base of the triangle situated along the vertebral column (the muscle’s origin) and the apex pointing toward the tip of the shoulder (the muscle’s insertion)  The muscles on both sides together form a trapezoid.

The superior fibers of trapezius, from the skull and upper portion of the vertebral column descend to attach to the lateral third of the clavicle and to the acromion of the scapula. Contraction of these fibers elevates the scapula. In addition, the superior and inferior fibers work together to rotate the lateral aspect of the scapula upward to raise the upper limbs above the head.(Overhead abduction).

Motor innervation of trapezius is by the accessory nerve (XI), which descends from the neck onto the deep surface of the muscle . Proprioceptive fibers from trapezius pass in the branches of the cervical plexus and enter the spinal cord at spinal cord levels C3 and C4.

Acting with levator scapulae, the upper fibres elevate the scapula and with it the point of the shoulder; acting with serratus anterior, trapezius rotates the scapula forward so that the arm can be raised above the head; and acting with the rhomboids, it retracts the scapula, bracing back the shoulder. With the shoulder fixed, trapezius may bend the head and neck backwards and laterally. Trapezius, levator scapulae, rhomboids and serratus anterior combine in producing a variety of scapular rotations

Clinical anatomy: testing Trapezius is palpated while the shoulder is shrugged against resistance.

13.  Rhomboideus:-Retract the scapula Supplied by dorsal Scapular nerve.

14. Clavicle:- The shaft is gently curved and in shape resembles the italic letter f, being convex forwards in its medial two-thirds and concave forwards in its lateral third.

The clavicle begins to ossify before any other bone in the body, and is ossified from three centres. The shaft of the bone is ossified in condensed mesenchyme from two primary centres, medial and lateral, which appear between the fifth and sixth weeks of intrauterine life, and fuse about the forty-fifth day. Cartilage then develops at both ends of the clavicle. The medial cartilaginous mass contributes more to growth in length than does the lateral mass: the two centres of ossification meet between the middle and lateral thirds of the clavicle. A secondary centre for the sternal end appears in late teens, or even early twenties, usually 2 years earlier in females (Fig. 49.2). Fusion is probably rapid but reliable data are lacking. An acromial secondary centre sometimes develops at c.18 to 20 years, but this epiphysis is always small and rudimentary and rapidly joins the shaft.

The clavicle is often fractured, commonly by indirect forces, as a result of a violent impact to the hand or shoulder. The break is usually at the junction of the lateral and intermediate thirds, where the curvature changes, for this is the weakest part of the bone. A fracture medial to the conoid tubercle interrupts weight transmission from the arm to the axial skeleton. The resulting deformity is caused by the weight of the arm, which acts on the lateral fragment through the coracoclavicular ligament and draws it downwards. The medial fragment, as a rule, is a little displaced.

image

The coracoclavicular ligament connects the clavicle and the coracoid process of the scapula. Though separate from the acromioclavicular joint, it is a most efficient accessory ligament, and maintains the apposition of the clavicle to the acromion. Its trapezoid and conoid parts, usually separated by fat or, frequently, a bursa, connect the medial horizontal part of the coracoid process and lateral end of the subclavian groove of the clavicle; these adjacent areas may even be covered by cartilage to form a coracoclavicular joint.

The coracoclavicular ligament stabilizes the acromioclavicular joint. In acromioclavicular dislocation, the ligament is torn and the scapula falls away from the clavicle. Dislocation readily recurs because of the flatness and orientation of the joint surfaces.

15.

image

All of the following are branches of subclavian artery except :
(A)Vertebral artery
(B)Thyrocervical trunk
(C)Subscapular artery—-axillary artery branch
(D)Internal thoracic artery

image

16. Deltoid:-     ORIGIN                                                                              INSERTION                                                       NERVE                                                              ACTION

Trapezius Superior nuchal line, external occipital protuberance, medial margin of the ligamentum nuchae, spinous processes of CVII to TXII and the related supraspinous ligaments Superior edge of the crest of the spine of the scapula, acromion, posterior border of lateral one-third of clavicle Motor spinal part of accessory nerve (CN XI). Sensory (proprioception) anterior rami of C3 and C4 Powerful elevator of the scapula; rotates the scapula during abduction of humerus above horizontal; middle fibers retract scapula; lower fibers depress scapula
Deltoid Inferior edge of the crest of the spine of the scapula, lateral margin of the acromion, anterior border of lateral one-third of clavicle Deltoid tuberosity of humerus Axillary nerve [C5,C6] Major abductor of arm (abducts arm beyond initial 15° done by supraspinatus); clavicular fibers assist in flexing the arm; posterior fibers assist in extending the arm

imageimage

The two most superficial muscles of the shoulder are the trapezius and deltoid muscles (Fig. 7.34 and Table 7.1). Together, they provide the characteristic contour of the shoulder:

  • trapezius attaches the scapula and clavicle to the trunk;
  • deltoid attaches the scapula and clavicle to the humerus

Trapezius is attached to all structures except :
(A)First rib
(B)Clavicle
(C)Scapula
(D)Occiput

Posted in Uncategorized | Tagged: , , , , , , , | 5 Comments »