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Vignette 1 of 5 A 3-month-old boy is brought to the emergency department by his parents because he has been vomiting for 4 days. The baby appears very ilI, with dry mucous membranes and poor skin turgor. He is poorly responsive during the examination. According to his mother, he has not been able to hold anything down for several days, and his diapers have been dry for almost 24 hours. The mother describes the vomiting as having been very forcefuI, and accompanied with gagging and retching. She did not notice any red-brown, black, or green discoloration to the emesis, and states that it just looked like formula. No other family members have been ilI, and when the mother called the child's daycare, she was told that no other children were ill with similar symptoms. Despite the vomiting, until today, the child has behaved as if he were very hungry, and would seek the bottle again shortly after vomiting. Which of the following would be most likely to account for the patient's problems? / A. Bacterial gastroenteritis / B. Esophageal reflux / C. Gastric ulcer / D. Pyloric stenosis / E. Viral gastroenteritis Explanation - Q: 1.1 Close The correct answer is D. This child most likely has hypertrophic pyloric stenosis, which causes obstruction of the pyloric channel secondary to muscular hypertrophy in the pyloric region. This condition may run in families, and most often does not present until the child is several weeks to months old. Hypertrophic pyloric stenosis has an incidence of about 1 of every 500 births, and a male predominance of 4-5 to 1. The vomiting may be so severe that the term "projectile" is appropriate. This child's presentation is typical. The absence of discoloration to the emesis indicates that it does not contain bile (and so the problem is above the ampulla of Vater in the duodenum) or blood. Both bacterial (choice A) and viral (choice E) gastroenteritis would usually be accompanied by significant nausea, and the child would not wish to eat after vomiting. Esophageal reflux (choice B) can cause a gentle regurgitation of formula, but does not cause severe vomiting with gagging and emesis. Gastric ulcer (choice C) would be very unusual in a child of this age. Physical examination also shows visible gastric peristaltic waves. Which additional finding should be sought on physical examination? / A. Multiple petechiae / B. OIive shaped mass / C. Pain on palpation in the upper left quadrant below the liver / D. Spider angiomas / E. Tenderness at McBurney's point Explanation - Q: 1.2 Close The correct answer is B. The most characteristic physical finding on abdominal examination in children with hypertrophic pyloric stenosis is the presence of a mass about the size and shape of a small olive, which is usually felt to the right of the umbilicus. This mass is most easily felt if the child is calm (or better still asleep) and gentle palpation is used to prevent guarding. The mass is produced by hypertrophy of the pyloric muscle. Multiple petechiae (choice A) would suggest a blood clotting problem. Pain below the liver (choice C) suggests gallstone disease (usually in adults). Spider angiomas (choice D) suggest alcoholic cirrhosis (usually in adults). Tenderness at McBurney's point (choice E) in the right lower quadrant suggests appendicitis. The patient's history of vomiting would be most likely to produce which of the following? / A. Metabolic acidosis with increased anion gap / B. Metabolic acidosis with normal anion gap / C. Metabolic alkalosis / D. Respiratory acidosis / E. Respiratory alkalosis Explanation - Q: 1.3 Close The correct answer is C. These children lose gastric hydrochloric acid in the vomitus, and consequently develop a metabolic alkalosis with low chloride levels. Other laboratory findings that may be seen are related to dehydration and include: high specific gravity in the urine, high BUN and creatinine, and hemoconcentration. Metabolic acidosis with increased anion gap (choice A) can be seen in diabetes mellitus, lactic acidosis, renal failure, and intoxication. Metabolic acidosis with normal anion gap (choice B) can be seen with diarrhea, renal tubular acidosis, and other renal disease. Respiratory acidosis (choice D) can be seen with depression of the respiratory center, severe lung disease, and diseases that impair lung expansion. Respiratory alkalosis (choice E) can be seen in voluntary or drug-induced hyperventilation or resulting from hyperventilation at high altitudes. Which of the following is the best choice for confirmation of the diagnosis? / A. Computed tomography / B. Magnetic resonance imaging / C. PIain x-ray film / D. Scintillation scan / E. Uitrasound Explanation - Q: 1.4 Close The correct answer is E. Most cases of hypertrophic pyloric stenosis are now being confirmed with abdominal ultrasound, which, in these cases, demonstrates a typical hypoechoic mass between the stomach and duodenum. An upper gastrointestinal series may also be helpful, if ultrasound studies are ambiguous. Computed tomography (choice A) and magnetic resonance imaging (choice B) are overly expensive and not required for diagnosis in this condition. Plain x-ray films (choice C) may show a stomach filled with air and fluid, but this is not considered as reliable a finding as the abdominal ultrasound studies. Scintillation scans (choice D) are usually used to evaluate the extent of bony disease. Which of the following treatments would best correct this child's disease? / A. IV fluids with 3 day restriction of oral intake / B. Gastric resection / C. Medical management with acetaminophen / D. Medical management with antacids / E. Pyloromyotomy Explanation - Q: 1.5 Close The correct answer is E. After inguinal hernia, the most common cause of gastrointestinal surgery in very young children is hypertrophic pyloric stenosis. The surgery that is done is called pyloromyotomy, and involves partially cutting through the pyloric muscle, to allow it to be spread apart with resultant dilation of the lumen of the pyloric channel. This operation only takes about 30 minutes to perform after anesthesia is induced, and most of the babies are allowed to go home within 24-48 hours. Gastric resection (choice B) is not required, and various forms of medical management (choices A, C, and D) will not correct the underlying problem (although medical stabilization before surgery is appropriate). Vignette 2 of 5 Over 50 children at an elementary school became violently ill several hours after eating lunch. AII of the affected children developed severe nausea and vomiting, and some additionally developed abdominal cramps and non-bloody diarrhea. AII of the students felt much better by the following morning. Which of the following items from the lunch would be most likely to be the cause of the food poisoning? / A. Carrot sticks / B. Chicken salad / C. Fresh pineapple / D. Lemonade / E. Whole wheat rolls Explanation - Q: 2.1 Close The correct answer is B. In most cases of food poisoning causing violent gastrointestinal symptoms, the culprit contains meat, cheese, milk or milk products, eggs, or salad dressing. In this case, the chicken salad is the most likely culprit. Fresh fruits and vegetables, such as the carrots (choice A) and pineapple (choice C), are less likely choices unless a salad dressing has been used. Lemonade (choice D) is too acidic to grow most bacteria, and most commercial soft drinks have enough preservatives in them to not be a problem, even if they have been badly stored for a few hours. Bread products (choice E) are also not usually implicated, unless they are moist due to being incorporated into a dessert or casserole. Gram's stain of a smear taken from the presumed source of the food poisoning shows abundant gram-positive cocci in grape-Iike clusters. Which of the following is the most likely causative organism? Explanation - Q: 2.2 Close The correct answer is C. "Gram-positive cocci in grape-like clusters" is the classic description used in test questions about Staphylococcus. Bacillus cereus(choice A) can cause food poisoning, but is a grampositive rod. Escherichia coli(choice B) can cause diarrheal illness related to infection, but is a gram-negative rod. Streptococcus pneumoniae(choice D) and S. pyogenes(choice E) are gram-positive cocci that usually occur in chains and are not a usual cause of food poisoning or diarrheal illness Which of the following is the most likely source of the bacteria? / A. Food preparer's hands / B. Infected animal supplying milk / C. Infected animal used for meat / D. Poorly cleaned bowl / E. Water used in food preparation Explanation - Q: 2.3 Close The correct answer is A. While in theory, staphylococci can enter a food specimen by any of the routes listed, in practice the most common source is bacteria from the food handler's skin. Staphylococcus aureus is present in small numbers on the skin of many individuals, and may be present in large numbers in persons with true staphylococcal skin infections. All commercial food handlers should use gloves, and people with impetigo (skin infection due to staphylococci) should not prepare food. The presentation of the case in these questions was based in part on a real staphylococcal food poisoning outbreak that occurred in Texas and has been reported by the US Food and Drug Administration. 16 elementary schools were served by the same central kitchen, and 1,364 of 5,825 children became poisoned. The culprit was the chicken salad. The previous day, frozen chickens had been boiled for 3 hours, deboned, and then cooled to room temperature with a fan. They were then ground into small pieces and placed in 12 inch deep aluminum pans (which may not have cooled quickly) where they were stored overnight in a walk-in refrigerator at a temperature thought to be 42-45 F. The next morning, the salad was prepared. The food was then transported in thermal containers to the various schools, where it was kept at room temperature for several hours before being served to the children. The investigators thought that the contamination probably occurred while the chickens were being deboned, and then the subsequent inadequate refrigeration for much of 24 hours allowed proliferation of the staphylococci, which were easily demonstrated in the chicken salad later. Which of the following is the most appropriate therapy to offer most patients who develop this type of food poisoning? / A. Bed rest only / B. IV cephalosporins / C. Oral ampicillin / D. Oral cephalosporins / E. Penicillin injection Explanation - Q: 2.4 Close The correct answer is A. Staphylococcal food poisoning is usually selflimited, and can be treated with bed rest alone. Antibiotics (choices B to E) are not indicated. Death occurs rarely, and when it does, the patient is almost always in a vulnerable group, such as the very young, the elderly, or the already seriously ill. Patients in these populations may require hospitalization with intravenous fluid support through the illness. Vignette 3 of 5 A 13-year-old girl is taken to the emergency department by her mother. The girl had awoken feeling ilI, and stayed home alone. When her mother returned from work, she found that her daughter had been vomiting more or less continuously all day. The mother was particularly concerned because her daughter seemed to be acting "weird" with an unusual degree of drowsiness and listlessness. When the physician attempts to interview the girI, she is very irritable, combative, and appears to be confused. Physical examination fails to demonstrate focal neurologic findings, but hepatomegaly is noted. No jaundice, fever, rash, or lymphadenopathy are noted. Drug screens are negative; screening serum chemistries demonstrate moderate elevations (4 times upper limit of normaI) of serum liver transaminases. By the time the laboratory results return, the girl has developed coma with progressive unresponsiveness. Emergency CT scan of the head demonstrates nonspecific findings including cerebral edema, gyral flattening, swollen white matter, and ventricular compression. Which of the following is the most likely diagnosis? / A. Kawasaki syndrome / B. Meningococcal meningitis / C. Reye syndrome / D. Rocky Mountain spotted fever / E. Wilson disease Explanation - Q: 3.1 Close The correct answer is C. Reye syndrome is a rare, but potentially devastating disease primarily affecting individuals less than 18 years old. Because of its rarity, it is likely to be misdiagnosed as meningitis, encephalitis, diabetes, drug overdose, sudden infant death syndrome, head trauma, renal or hepatic failure, poisoning, or a psychiatric disturbance. In infants, it should be suspected when diarrhea (but not necessarily vomiting), respiratory disturbances (hyperventilation, apneic episodes), seizures, or hypoglycemia are accompanied by elevated liver transaminases (AST, ALT) in the absence of jaundice. In children, adolescents, and the rare adult patient, suspect Reye when you see a cluster of severe vomiting, elevated serum transaminases without jaundice, and signs of neurologic dysfunction. This patient's CT findings are typical, and nonspecifically reflect marked brain edema with compression of fluid-filled spaces such as the ventricles and meningeal spaces. Treatment of Reye syndrome is supportive, as no specific therapy is available. Patients may recover completely, be left with mild to severe residual neurologic defects, or die. Kawasaki syndrome (choice A) is a sometimes very severe febrile illness of children that may be associated with lymphadenopathy, rash, and late development of coronary artery aneurysms secondary to polyarteritis. Meningococcal meningitis (choice B) can present fulminantly, as in this case, but nuchal rigidity would be noted in the case presentation and a CT scan would probably show meningeal thickening. Rocky Mountain spotted fever (choice D) can cause a fulminant illness with a prominent petechial rash. Wilson disease (choice E) can cause both psychiatric and hepatic dysfunction, but tends to become symptomatic over a period of decades. Marked elevation of which of the following would be most helpful in confirming the suspected diagnosis? / A. BIood free erythrocyte protoporphyrin / B. BIood methemoglobin / C. Serum ammonia / D. Serum somatomedin C / E. Urine vanillylmandelic acid Explanation - Q: 3.2 Close The correct answer is C. Patients with Reye syndrome often have markedly elevated serum NH4+ levels as a consequence of the liver dysfunction. These high ammonia levels probably substantially contribute to the altered mental status seen commonly in Reye patients. Erythrocyte protoporphyrin (choice A) is increased in some forms of porphyria. Methemoglobin (choice B) is an oxidized form of hemoglobin that can be seen in hemolytic anemias. Somatomedin C (choice D) elevation can be seen in gigantism and acromegaly. Vanillylmandelic acid (choice E) can be elevated in pheochromocytoma. This patient's disease was most likely preceded by which of the following illnesses? / A. Crohn disease / B. Diabetes mellitus / C. Hypothyroidism / D. Influenza / E. Juvenile rheumatoid arthritis Explanation - Q: 3.3 Close The correct answer is D. Many patients who develop Reye syndrome have a recent history of a febrile viral illness, most notably influenza and varicella (chicken pox). How this predisposes for Reye syndrome is unclear, but the link appears compelling. Note that patients who have preceding chickenpox may still have the rash, as Reye syndrome typically develops on the 5th or 6th day of the illness in these patients. Reye syndrome does not appear to be an autoimmune disease, and has no links to other diseases with a strong autoimmune component, including Crohn disease (choice A), diabetes mellitus type I (choice B), and juvenile rheumatoid arthritis (choice E). Reye syndrome is also unrelated to hormonal disorders such as hypothyroidism (choice C). Ingestion of which of the following is most likely to have contributed to the patient's illness? / A. Acetaminophen / B. Aspirin / C. Coffee / D. Pseudoephedrine / E. Tea Explanation - Q: 3.4 Close The correct answer is B. Aspirin and salicylate use is thought to increase the risk of developing (still very rare) Reye syndrome by 35-fold. While few parents now give young children aspirin, many teenagers or their parents may consider the teens to be "adults" and use aspirin for fever and discomfort control. Also, many over-the-counter anti-nausea medications may contain salicylates, and patients may thus be exposed unknowingly to them. The other agents listed in the choices have no known link to Reye syndrome. If this patient's liver were biopsied and a sample sent for electron microscopy, which of the following would most likely be seen? / A. Abnormally formed cilia / B. Enlarged mitochondrial with disrupted cristae / C. Linear inclusions in macrophages / D. Membrane-bound vacuoles with complex crystalline structures / E. Prominent, Iong microvilli Explanation - Q: 3.5 Close The correct answer is B. While the pathophysiology of Reye syndrome is still poorly understood, severe mitochondrial dysfunction (most prominent in brain and liver) is a striking feature and is confirmed by often marked morphological changes in mitochondria observed by electron microscopy. Abnormal cilia (choice A) in the respiratory epithelium is a feature of Kartagener syndrome, characterized by bronchiectasis and sometimes, situs inversus. Linear inclusions in macrophages (choice C) in the brain are a feature of the hereditary condition, Krabbe disease. Membrane-bound vacuoles with a complex crystalline structure (choice D) can be seen in the brain of patients with the hereditary condition, metachromatic leukodystrophy. Prominent, long microvilli (choice E) are a feature of mesotheliomas. Vignette 4 of 5 A 65-year-old man is struck by a car as he is staggering across the street after a night of binge drinking. When the ambulance arrives, he is noted to be belligerent and combative. A Iarge left temporal laceration is observed. On arrival to the emergency department, his blood pressure is 148/78 mm Hg, his pulse is 89/min, and his oxygen saturation is 96%. He continues to be uncooperative, so only a cursory physical examination is performed, which reveals a 6 cm left temporal Iaceration and no other gross abnormalities. The laceration is sewn closed at the bedside, and the patient left to rest. An hour later the patient's speech becomes more slurred; he begins vomiting, and is given prochlorperazine. An hour later, he is found to be unresponsive. His blood pressure is 194/100 mm Hg and his pulse is 55/min. His left pupil is 6 mm and non-reactive and his right pupil is 3 mm and reactive to light. He localizes to pain in his left upper and lower extremities, but exhibits no movement in his right upper and lower extremities. Which of the following is the most likely diagnosis? / A. AIcohol toxicity / B. AIcohol withdrawal / C. Horner syndrome / D. Subfalcine (cingulate) herniation / E. Uncal herniation Explanation - Q: 4.1 Close The correct answer is E. Uncal herniation occurs when a mass lesion, such as a subdural hematoma, causes increased intracranial pressure and displaces the brain downward. The uncus and parahippocampal gyrus are pushed over the tentorial edge, where they compress the brain stem, causing contralateral hemiparesis. The uncus also compresses the ipsilateral third cranial nerve, as it enters the interpeduncular cistern at the midbrain/pons junction, resulting in an ipsilateral third nerve palsy. Signs and symptoms of increased intracranial pressure often are present prior to a herniation syndrome. These include headache, nausea/vomiting, agitation, lethargy, and eventually, coma. There may be a decrease in heart rate and an increase in blood pressure as well. Alcohol toxicity (choice A) is characterized by disinhibition, emotional lability, slurred speech, and ataxia, followed by loss of consciousness and then coma. It would be unusual for a conscious intoxicated patient to progress to coma without consuming more alcohol. Alcohol withdrawal (choice B) usually occurs 2-5 days after the last drink. Autonomic hyperactivity, characterized by tachycardia, hypertension, tremors, and anxiety, occurs first. This is followed by delirium tremens, hallucinations, and confusion. Horner syndrome (choice C) results from a disruption of the sympathetic fibers that originate from the hypothalamus. These fibers travel inferiorly to synapse on second-order neurons in the intermediolateral column of the spinal cord, then synapse on third-order neurons in the superior cervical sympathetic ganglion, to finally innervate the smooth muscles of the eyelids, pupil, and sweat glands of the face and forehead. Interruption of these fibers, which can occur with a Pancoast tumor, results in ipsilateral ptosis, miosis, and anhidrosis. Subfalcine (cingulate) herniation (choice D) occurs when a mass lesion causes the cingulate gyrus to move under the free edge of the falx, and the ipsilateral foramen of Monro becomes trapped. This causes an ipsilateral large lateral ventricle and a contralateral small lateral ventricle. What is the mechanism most likely responsible for the patient's unilateral pupillary dilation? A. Autonomic hyperactivity due to alcohol withdrawal B. Prochlorperazine (Compazine) C. Unilateral compression of preganglionic parasympathetic fibers originating from the Edinger-Westphal nucleus / D. Unilateral compression of postganglionic sympathetic fibers originating from the superior cervical ganglion / E. Unilateral compression of the frontal eye fields / / / Explanation - Q: 4.2 Close The correct answer is C. The Edinger-Westphal nucleus gives rise to preganglionic parasympathetic fibers. These fibers leave the midbrain and travel on the dorsal superficial aspect of the oculomotor nerve. They then synapse on the ciliary ganglion. The ciliary ganglion then gives rise to postganglionic parasympathetic fibers, which terminate in the ciliary body and the iris to cause miosis. Interruption of this pathway, such as when the uncus compresses these fibers in uncal herniation, results in unopposed sympathetic input to the ipsilateral eye, which results in ipsilateral pupillary dilation. Autonomic hyperactivity due to alcohol withdrawal (choice A) usually occurs 2-5 days after the last drink. It is manifested as tachycardia, hypertension, anxiety, and tremors. Prochlorperazine (Compazine) (choice B) is a phenothiazine antiemetic, which selectively antagonizes dopamine D2 receptors. It can have atropine-like side effects, as well as cause photosensitivity and even oculogyric crisis. It would not cause a unilateral papillary dilation. Unilateral compression of postganglionic sympathetic fibers originating from the superior cervical ganglion (choice D) interrupts the sympathetic input to the ipsilateral eye and half of the face, resulting in a Horner's syndrome (miosis, ptosis, anhidrosis). Unilateral compression of the frontal eye fields (choice E) results in ipsilateral eye deviation. The frontal eye fields (Area 8) are located in the caudal middle frontal gyrus and are responsible for the initiation of saccades (rapid eye movements to a target of behavioral importance). Stimulation of area 8 results in conjugate eye deviation to the contralateral side (away from the stimulation). A lesion involving area 8 causes a transient conjugate eye deviation to the ipsilateral side (toward the lesion). Which of the following is a common side effect of prochlorperazine? / A. Diarrhea / B. Disulfiram-Iike reaction / C. Drowsiness / D. Miosis / E. Urinary urgency Explanation - Q: 4.3 Close The correct answer is C. Prochlorperazine is a phenothiazine antiemetic, which commonly causes drowsiness, as well as dizziness, and can produce extrapyramidal side effects. For these reasons, it should not be used in patients with an altered mental status, as it further depresses the patient's sensorium and makes it more difficult for the treating physician to accurately follow the patient's neurologic examination. It also has atropine-like side effects, resulting in dry mouth, constipation, and urinary retention. None of the other choices are side effects of prochlorperazine. Which of the following is the most likely cause for the patient's unresponsiveness? / A. Injury to both of the mamillary bodies / B. Injury to the left parietal lobe / C. Injury to the left subthalamic nucleus / D. Injury to the reticular activating system / E. Injury to the right parietal lobe Explanation - Q: 4.4 Close The correct answer is D. Tonic input from the reticular activating system (RAS) keeps the brain turned "on." An injury to the RAS, such as during uncal herniation, causes the patient to fall into a coma. The RAS is located in the middle and lateral pons and midbrain. It sends signals to the subcortical structures (especially the thalamus), which then send diffuse inputs to the cortex. The cortex, in turn, sends positive feedback inputs back to the RAS. The RAS also sends signals to the spinal cord to maintain tone and activate the spinal reflexes. Injury to the mamillary bodies (choice A) is seen in Wernicke-Korsakoff encephalopathy. This disorder is seen in alcoholics with B1 (thiamine) deficiency. Wernicke encephalopathy is characterized by psychosis, ophthalmoplegia, and confusion. Korsakoff syndrome is characterized by memory loss, confabulation, and confusion. Injury to the left parietal lobe (choice B) can result in a Gerstmann syndrome. Gerstmann syndrome is characterized by right/left confusion, finger agnosia, acalculia, and agraphia. Injury to the left subthalamic nucleus (choice C) results in contralateral sudden limb flailing (hemiballismus). Injury to the right parietal lobe (choice E) can result in a left hemineglect. On further examination, the patient exhibits decerebrate (extensor) posturing in his upper and lower extremities. What is the most likely mechanism for this? / A. An injury below the level of the vestibular nuclei / B. An injury between the red nucleus and the vestibular nuclei / C. An injury to the midbrain above the red nucleus / D. An injury to the posterior limb of the left internal capsule / E. An injury to the vermis Explanation - Q: 4.5 Close The correct answer is B. Decerebrate (extensor) posturing is characterized by extension, adduction, and pronation of the arms, extension of the legs, and plantar flexion of the feet. It results from a lesion of the rubrospinal tract, originating from the red nucleus, which maintains flexor tone in the arms and legs. The vestibulospinal tract, which maintains extensor tone, is then unopposed, resulting in the extensor posture. An injury below the level of the vestibular nuclei (choice A) results in contralateral hemiparesis (or quadriparesis if the lesion involves both corticospinal tracts), but not in posturing. An injury to the midbrain above the red nucleus (choice C) results in contralateral hemiparesis (or quadriparesis if the lesion involves both corticospinal tracts) and decorticate (flexor) posturing due to dominance of the rubrospinal tract, which maintains flexor tone in the arms and legs. An injury to the posterior limb of the left internal capsule (choice D) results in a contralateral hemiparesis and decorticate (flexor) posturing due to dominance of the rubrospinal tract, which maintains flexor tone in the arms and legs. An injury to the vermis (choice E) results in truncal ataxia, scanning speech, and hypotonia. Vignette 5 of 5 A 33-year-old woman presents to the emergency department complaining of nausea and vomiting. She states that she has been having significant nausea that has been worsening over the past 2 weeks. Over the past 2 days, she has had 2 episodes of vomiting. She also notes increased fatigue. She has no abdominal pain or vaginal bleeding. She has no other complaints. Her past medical history is significant for occasional migraine headaches. She has never had surgery. She takes acetaminophen as needed for headache, and has no known drug allergies. She works as a lawyer at a local firm and lives with her husband of three years. She has no family history of cancer or heart disease. Her vital signs are stable. Examination is significant for a bluish-appearing cervix on speculum examination. The remainder of the examination, including the abdominal examination, is benign. Laboratory evaluation shows: Urine hCG: positive Leukocytes: 9,000/mm3 Hematocrit: 41% PIatelets: 250,000/mm3 Pelvic ultrasound demonstrates a gestational sac with yolk sac and fetal pole surrounded by myometrium. There is a heart rate of 154 beats per minute. Which of the following is the most likely diagnosis? / A. Appendicitis / B. Complete hydatidiform mole / C. Ectopic pregnancy / D. Intrauterine pregnancy / E. Spontaneous abortion Explanation - Q: 5.1 Close The correct answer is D. This patient's presentation, exam findings, and studies are all consistent with a diagnosis of intrauterine pregnancy. First, her presenting complaints of nausea, vomiting, and fatigue are consistent with a first trimester pregnancy. Approximately 80% of pregnant women experience some nausea during the pregnancy, especially in the first trimester. This nausea is most commonly called "morning sickness" but it can occur at any time during the day. Fatigue is also a common first trimester complaint. On examination she has a bluish-appearing cervix. This is called "Chadwick's sign" and it is another clue that she is pregnant. Most definitively, though, she has a positive urine pregnancy test. With this positive test, the diagnosis is narrowed to intrauterine pregnancy, ectopic pregnancy, or spontaneous abortion, with mole also being a consideration. The ultrasound that demonstrates an intrauterine pregnancy fully establishes the diagnosis. Appendicitis (choice A) represents an infection of the appendix. Patients with appendicitis most commonly present with symptoms and signs of infection, including abdominal pain, fever and chills, abdominal tenderness, elevated temperature, and leukocytosis. A patient with a complete hydatidiform mole (choice B) will not have an intrauterine pregnancy with a fetal heart rate visualized on ultrasound examination. A complete mole often appears as a "snowstorm" pattern on pelvic ultrasound. It is essential to "think ectopic!" whenever a woman of childbearing age presents for medical attention. In fact, this sign ("think ectopic!") and other such similar signs can be seen in many emergency rooms. However, patients with ectopic pregnancy (choice C) usually complain of abdominal pain or vaginal bleeding. On examination, they will often have abdominal and adnexal tenderness. Pelvic ultrasound will show no intrauterine pregnancy. This patient, with a gestational sac, yolk sac, and fetus seen surrounded by myometrium (that is, within the uterus) can be diagnosed with an intrauterine pregnancy. Most patients with spontaneous abortions (choice E) present with vaginal bleeding a passage of tissue (products of conception.) On ultrasound, no viable pregnancy (i.e., an intrauterine pregnancy with a normal heart rate) is seen. This patient could possibly go on to have a spontaneous abortion, but, at this point, she can be diagnosed with an intrauterine pregnancy. During early pregnancy, the trophoblastic cells secrete which of the following hormones in order to maintain the corpus Iuteum? / A. Estrogen / B. Human chorionic gonadotropin (hCG) / C. Luteinizing hormone (LH) / D. Progesterone / E. Testosterone Explanation - Q: 5.2 Close The correct answer is B. At approximately the midpoint of the menstrual cycle, the ovum is expelled. Once this occurs, the surrounding granulosa and theca cells undergo luteinization and begin to secrete a large amount of estrogen and progesterone. This mass of hormone secreting cells is known as the corpus luteum (because of its yellow color). If pregnancy does not occur, the corpus luteum will persist for 14 days, after which point it degenerates. With the degeneration of the corpus luteum, hormonal levels drop, the endometrium sloughs, and menstruation occurs. If a pregnancy does occur, the trophoblastic cells of the pregnancy will secrete human chorionic gonadotropin (hCG). This hormone goes to the corpus luteum and prevents its degeneration, signaling it to continue its excretion of estrogen and progesterone to maintain an environment that is favorable for pregnancy. The presence of human chorionic gonadotropin forms the basis for the urine and serum pregnancy test. hCG steadily increases over the first several weeks of the pregnancy, reaching a peak at approximately 10 weeks. After that, hCG levels decrease gradually during the remainder of the pregnancy. During early pregnancy, most women experience some nausea. One of the leading theories for the cause of this nausea is the hormone hCG, because the nausea of early pregnancy appears to mirror the rise and fall of the hCG levels--peaking at roughly 10 weeks and improving after that. Estrogen (choice A) and progesterone (choice D) are produced by the corpus luteum during early pregnancy. The corpus luteum does not degenerate in a pregnant woman, as it does in the nonpregnant woman, because the trophoblastic cells secrete human chorionic gonadotropin (hCG). After the first months of pregnancy, the placenta takes over the role of secreting the large amounts of estrogen and progesterone that are needed to continue a healthy pregnancy. Once the placenta has taken over this role, the corpus luteum degenerates. Luteinizing hormone (LH) (choice C) is produced by the anterior pituitary gland. Its rate of secretion is controlled mainly by the hypothalamus, through hypothalamic luteinizing hormone-releasing hormone (LHRH, also called GnRH) secretion. The LH surge, which occurs roughly at the midpoint of the menstrual cycle, appears to cause ovulation, which occurs approximately 24 hours after the surge. LH also appears to induce the theca and granulosa cells to become the corpus luteum. Testosterone (choice E) is formed by the interstitial cells of the testicles. It is not known to be secreted by trophoblastic cells to maintain the corpus luteum. Which of the following is a derivative of the ectoderm of the trilaminar embryo? / A. Bone / B. Germ cells / C. Muscle / D. Spinal cord / E. Spleen Explanation - Q: 5.3 Close The correct answer is D. The neural plate, a thickened area of ectoderm, gives rise to the nervous system. The first step is the development of a groove in the neural plate. On either side of this groove are the raised neural folds. These neural folds then begin to fuse in the midline at approximately the midpoint of the neural plate. Fusion proceeds in a rostral and caudal direction; once completed, there still remains an open area of the "tube" at both the rostral and caudal ends. These openings are referred to as the rostral and the caudal neuropore. The rostral neuropore closes around day 26 and the caudal neuropore closes on approximately day 28. With the closure of the caudal neuropore, closure of the neural tube is completed. It has been convincingly shown that folic acid plays an important role in the closure of the neural tube. By giving women of childbearing age folic acid supplements, the rate of neural tube defects can be reduced dramatically. Yet, based on the embryology of the neural tube (with closure of the tube roughly by day 28), it is obvious that in order for folic acid supplementation to work, it should be started pregestationally. Unfortunately, most women do not seek prenatal care until after the neural tube has undergone its period of closure. Bone (choice A), muscle (choice C), and spleen (choice E) are all derivatives of the mesoderm. This mesoderm is formed at the end of the second week post-fertilization, when some cells of the primitive streak migrate laterally between the endodermal and the ectodermal layer. Germ cells (choice B) are derived from the endodermal layer of the trilaminar embryo. They migrate as primordial sex cells from the endoderm of the yolk sac to the urogenital ridge. Assays for serum human chorionic gonadotropin (hCG) are commonly used as a pregnancy test. However, there have been several reported cases of false positive results, that is, women who test positive and are told that they are pregnant but later turn out not to be. If the false positive rate of serum hCG for detecting pregnancy is < 0.5%, then what is the specificity of the test? / A. < 0.5% / B. > 0.5% / C. < 99.5% / D. > 99.5% / E. It cannot be determined from the information given Explanation - Q: 5.4 Close The correct answer is D. Serum and urine hCG tests are widely used to determine if a patient is pregnant. The development and use of these tests has been absolutely essential for the diagnosis and management of a variety of conditions including pregnancy, ectopic pregnancy, spontaneous abortion, gestational trophoblastic neoplasia, and some malignancies. However, it is important to always remember that no test is 100% perfect. Numerous case reports attest to the fact that using hCG to test for pregnancy will sometimes yield incorrect results. A false positive result refers to the situation when the test states that the patient does have the disease or condition (in this case pregnancy) when, in fact, the patient does not have the condition. A false positive rate of 0.5% means that out of every 100 people who are not pregnant and take the pregnancy test, 0.5 will be told that they are pregnant. Multiplying this result by 2 (to get rid of the 0.5 person concept), it means that of every 200 people who are not pregnant, 1 will be falsely told that they are. A false-positive rate of < 0.5%, therefore, means that <1 nonpregnant person per 200 nonpregnant people that take the test will be told that they are pregnant. The specificity of a test represents the percentage of individuals who do not have a disease (or condition like pregnancy) who test negative by the diagnostic test. Staying with the above example, if 200 people who are not pregnant take the test, 199 of them will be told that they are not pregnant. This represents a specificity of 99.5%. If the false positive rate is <0.5% then the specificity is >99.5%. In general, the false positive rate (FPR) can be calculated by the formula FPR = (1-specificity).