Download Vignette 1 of 5

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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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).