A 27-year-old woman goes
to an emergency room with severe abdominal pain. She had previously experienced
similar episodes of pain that
Iasted several hours to a
few days, but this episode is the most severe. She has also been experiencing
nausea, vomiting, and constipation.
The physician is left with
the impression that she is agitated and somewhat confused, and an accurate
history is difficult to elucidate. The
patient is sent for
emergency laparotomy, but no pathology is noted at surgery. Following the unrevealing
surgery, an older surgeon
comments that he had once
seen a similar case that was actually due to porphyria.
Question
1 of 5
The porphyrias are
biochemical abnormalities in which of the following pathways?
/ A. GIycogen degradation
/ B. Heme synthesis
/ C. Lipoprotein degradation
/ D. Nucleotide degradation
/ E. Urea cycle
|
Explanation - Q: 1.1
|
|
The correct answer is B. The porphyrias are a
group of rare, related diseases that have in common a block in the heme
synthesis pathway. The block is usually partial rather than complete, and
thus many of these patients have only intermittent symptoms. Most cases of
porphyria present with either a neurovisceral pattern (including both
psychiatric symptoms and abdominal pain) or with photosensitive skin lesions.
These two patterns are associated with different forms of porphyria.
Associate abnormalities of glycogen degradation (choice
A) with the glycogen storage diseases, such as von Gierke disease, Pompe
disease, and Forbes disease.
Associate abnormalities of lipoprotein degradation (choice
C) with some forms of hyperlipoproteinemia (notably Type I).
Associate abnormalities of nucleotide degradation (choice
D) with gout and Lesch-Nyhan syndrome.
Associate abnormalities of the urea cycle (choice E)
with congenital hyperammonemia, citrullinemia, and argininosuccinic acidemia.
|
A 27-year-old woman goes
to an emergency room with severe abdominal pain. She had previously experienced
similar episodes of pain that
Iasted several hours to a
few days, but this episode is the most severe. She has also been experiencing
nausea, vomiting, and constipation.
The physician is left with
the impression that she is agitated and somewhat confused, and an accurate
history is difficult to elucidate. The
patient is sent for
emergency laparotomy, but no pathology is noted at surgery. Following the
unrevealing surgery, an older surgeon
comments that he had once
seen a similar case that was actually due to porphyria.
Question
2 of 5
Following the surgery, the
decision is made to screen for the porphyrias that cause acute neurovisceral
symptoms. Which of the following
tests would be most likely
to be used?
/ A. Erythrocyte porphyrins
/ B. Total fecal porphyrins
/ C. Total plasma porphyrins
/ D. Total urinary porphyrins
/ E. Urinary porphobilinogen
|
Explanation - Q: 1.2
|
|
The correct answer is E. The acute neurovisceral
porphyrias are those that tend to present with severe abdominal pain, often
accompanied by neuropsychiatric symptoms. The best tests to use for screening
of these diseases are urinary porphobilinogen (PBG, either random or 24 hour)
and urinary delta-aminolevulinic acid (
Erythrocyte porphyrins (choice A) are used for
follow-up in the photosensitive types of porphyria.
Total fecal porphyrins (choice B) are used for
follow-up evaluation after screening tests for either the photosensitive
porphyrias or the acute neurovisceral porphyrias are positive.
Total plasma porphyrias (choice C) are useful
for first line screening of the photosensitive porphyrias, and are used for
further evaluation after screening in the acute neurovisceral porphyrias.
Total urinary porphyrins (choice D) are used for
further evaluation after screening for acute neurovisceral porphyrias.
|
A 27-year-old woman goes
to an emergency room with severe abdominal pain. She had previously experienced
similar episodes of pain that
Iasted several hours to a
few days, but this episode is the most severe. She has also been experiencing
nausea, vomiting, and constipation.
The physician is left with
the impression that she is agitated and somewhat confused, and an accurate
history is difficult to elucidate. The
patient is sent for
emergency laparotomy, but no pathology is noted at surgery. Following the
unrevealing surgery, an older surgeon
comments that he had once
seen a similar case that was actually due to porphyria.
uestion 3
of 5
Which of the following are
the three most common forms of porphyria?
/ A. Acute intermittent porphyria, erythropoietic protoporphyria,
and porphyria cutanea tarda
/ B. Acute intermittent porphyria, hepatoerythropoietic porphyria,
and variegate porphyria
/ C. Congenital erythropoietic porphyria, delta-aminolevulinic acid
dehydratase-deficient porphyria, and hepatoerythropoietic porphyria
/ D. Erythropoietic protoporphyria, hereditary coproporphyria, and
porphyria cutanea tarda
/ E. Hereditary coproporphyria, variegate porphyria, and X-Iinked
sideroblastic anemia
|
Explanation - Q: 1.3
|
|
The correct answer is A. The porphyrias are
complex diseases that can easily appear overwhelming. A very useful point to
know (both clinically and for the USMLE) is that the three most common forms
are acute intermittent porphyria, erythropoietic protoporphyria, and
porphyria cutanea tarda. Acute intermittent porphyria tends to present with
acute neurovisceral symptoms. Erythrocytic protoporphyria tends to present
acutely with painful skin lesions. Porphyria cutanea tarda tends to present
with chronic blistering skin lesions. The other types listed in various
choices are also porphyrias, but are less common.
|
A 27-year-old woman goes
to an emergency room with severe abdominal pain. She had previously experienced
similar episodes of pain that
Iasted several hours to a
few days, but this episode is the most severe. She has also been experiencing
nausea, vomiting, and constipation.
The physician is left with
the impression that she is agitated and somewhat confused, and an accurate
history is difficult to elucidate. The
patient is sent for
emergency laparotomy, but no pathology is noted at surgery. Following the
unrevealing surgery, an older surgeon
comments that he had once
seen a similar case that was actually due to porphyria.
uestion 4
of 5
This patient is found to
have increased levels of both delta-aminolevulinic acid (ALA
demonstrate low PBG
deaminase in erythrocytes. AIso, additional history is elicited, revealing that
the woman had started a very low
carbohydrate diet about
one week before being admitted to the hospitaI. Which of the following is the
most likely diagnosis?
/ A. Acute intermittent porphyria
/ B. Congenital erythropoietic porphyria
/ C. Erythropoietic protoporphyria
/ D. Porphyria cutanea tarda
/ E. X-Iinked sideroblastic anemia
|
Explanation - Q: 1.4
|
|
The correct answer is A. These laboratory
findings are most consistent with acute intermittent porphyria, which is due
to PBG deaminase deficiency. Patients usually, but not always, have a
deficiency of erythrocyte PBG deaminases. (Some cases have also been
described in which the enzyme deficiency is limited to liver.) The condition
is an autosomal dominant disorder that typically becomes symptomatic in women
after puberty, and then often only if a precipitating event (dieting, use of
certain drugs, premenstrual) is also present. Symptoms during the attacks can
include abdominal symptoms (pain, nausea, vomiting, constipation, diarrhea,
abdominal distension, ileus), which are thought to be due to the effects of
this condition on visceral nerves. Other symptoms that may be mediated
neurologically include incontinence, urinary retention, tachycardia,
diaphoresis, hypertension, muscle weakness, psychiatric symptoms, seizures,
and rarely, severe paralysis, respiratory insufficiency, and death. Both
intravenous glucose (oral is often inadequate due to poor intestinal
function) and exogenous heme supplementation can suppress the heme
biosynthetic mechanism, and tend to ameliorate the acute attack. Patients
should be cautioned to diet gently, as intense dieting can precipitate
attacks.
Congenital erythropoietic porphyria (choice B)
is characterized by severe skin blistering that usually begins after birth,
pink to dark-brown urine, normal ALA and PBG, and increased porphyrins
(primarily uroporphyrin I and coproporphyrin I) in urine, plasma, and
erythrocytes.
Erythropoietic protoporphyria (choice C) is
characterized by cutaneous photosensitivity that begins early in life and
high protoporphyrin in erythrocytes and bone marrow.
Porphyria cutanea tarda (choice D) is
characterized by photosensitivity with skin blistering, elevated plasma
porphyrins, and elevated urine porphyrins (mostly uroporphyrin and
heptacarboxylporphyrin).
The very rare X-linked sideroblastic anemia (choice
E), due to a deficiency of delta-aminolevulinic acid synthase, can
clinically resemble acute intermittent porphyria, and is characterized by
elevated levels of urinary
|
A 27-year-old woman goes
to an emergency room with severe abdominal pain. She had previously experienced
similar episodes of pain that
Iasted several hours to a
few days, but this episode is the most severe. She has also been experiencing
nausea, vomiting, and constipation.
The physician is left with
the impression that she is agitated and somewhat confused, and an accurate
history is difficult to elucidate. The
patient is sent for
emergency laparotomy, but no pathology is noted at surgery. Following the
unrevealing surgery, an older surgeon
comments that he had once
seen a similar case that was actually due to porphyria.
Question
5 of 5
Which of the following
drugs would be most likely to induce an attack of abdominal pain in this
patient?
/ A. Acetaminophen
/ B. Aspirin
/ C. Barbiturate
/ D. GIucocorticoid
/ E. Insulin
|
Explanation - Q: 1.5
|
|
The correct answer is C. Some symptomatic
episodes of acute porphyria (including acute intermittent porphyria,
hereditary coproporphyria, variegate porphyria, and aminolevulinic acid
dehydratase porphyria) are triggered by drug ingestion, and administration of
drugs to undiagnosed patients can cause an acute exacerbation of an ongoing
attack of acute porphyria. Drugs considered unsafe for use in these patients
notably include alcohol, anticonvulsants, barbiturates, many other sedatives,
and sulfonamide antibiotics. Of particular concern are the sedative agents,
since it may be very tempting to give an obviously agitated patient a
sedative to allow easier examination of the patient. Many other drugs are
also on the lists of potentially dangerous drugs in these patients. Once the
diagnosis is established, the patient should be instructed to always inform
her/his physician of her condition, and ask that the safety of drugs
prescribed in patients with porphyria be checked. Many of the drugs that can
induce or exacerbate an attack of porphyria do so by increasing the activity
of the cytochrome P450 system, which indirectly triggers an increase in heme
biosynthesis. The other medications listed in the choices are
"safe" in these patients.
|
A 47-year-old woman
presents to the emergency department with cramping/colicky abdominal pain. The
current episode of pain began
several hours ago,
following a fatty meaI. The pain began slowly, and rose in intensity to a
plateau over the course of several hours. The
patient reports that she
had had several other episodes of similar pain during the past several months,
with long intervening periods of
freedom from pain. On
physical examination, she is noted to have tenderness to deep palpation in the
right upper quadrant of the abdomen
near the rib cage. The
patient also reports that she is experiencing shoulder/back pain at a site she
identifies near the right lower scapula, but
no tenderness can be
elicited during the back and shoulder examination.
Question
1 of 7
Which of the following organs
is the most likely source of this woman's pain?
/ A. Appendix
/ B. Diaphragm
/ C. Esophagus
/ D. Gallbladder
/ E. Stomach
|
Explanation - Q: 2.1
|
|
The correct answer is D. This woman most likely
has gallstones. Cholelithiasis, or the formation of calculi (gallstones)
within the gallbladder, is very common in the
The appendix (choice A) would most likely cause
lower abdominal pain.
Pain from irritation of the diaphragm (choice B)
can cause right upper quadrant pain and referred pain in the supraclavicular
area (rather than the subscapular pain of biliary colic). The absence of
right upper quadrant tenderness to palpation, and the history of pain after a
fatty meal also argue against this diagnosis.
Esophageal pain (choice C) related to
regurgitation of gastric contents (heartburn) can occur postprandially, but
tends to radiate into the neck, throat, or even face.
Peptic ulcer pain of gastric origin (choice E)
is usually described as causing burning, gnawing, or hunger, and may be
relieved by eating.
|
A 47-year-old woman
presents to the emergency department with cramping/colicky abdominal pain. The
current episode of pain began
several hours ago,
following a fatty meaI. The pain began slowly, and rose in intensity to a
plateau over the course of several hours. The
patient reports that she
had had several other episodes of similar pain during the past several months,
with long intervening periods of
freedom from pain. On
physical examination, she is noted to have tenderness to deep palpation in the
right upper quadrant of the abdomen
near the rib cage. The
patient also reports that she is experiencing shoulder/back pain at a site she
identifies near the right lower scapula, but
no tenderness can be
elicited during the back and shoulder examination.
Question 2
of 7
Which of the following
techniques would be most appropriate to demonstrate the patient's most likely
diagnosis?
/ A. Colonoscopy
/ B. CT scan of the abdomen
/ C. Esophagoduodenoscopy
/ D. MRI scan of the abdomen
/ E. UItrasonography
|
Explanation - Q: 2.2
|
|
The correct answer is E. Real-time
ultrasonography, with 98% sensitivity and 95% specificity, is considered the
method of choice for diagnosing possible gallbladder stones.
Colonoscopy (choice A) and esophagoduodenoscopy (choice
C) might be helpful for excluding alternative diagnoses, but would not
themselves establish a diagnosis of gallstone disease.
CT (choice B) and MRI (choice D) scans of
the abdomen are expensive tests whose use is not warranted, since real-time
ultrasonography performs as well or better.
|
*** Copy file lists and folder trees from Explorer ***
A 47-year-old woman
presents to the emergency department with cramping/colicky abdominal pain. The
current episode of pain began
several hours ago,
following a fatty meaI. The pain began slowly, and rose in intensity to a
plateau over the course of several hours. The
patient reports that she
had had several other episodes of similar pain during the past several months,
with long intervening periods of
freedom from pain. On
physical examination, she is noted to have tenderness to deep palpation in the
right upper quadrant of the abdomen
near the rib cage. The
patient also reports that she is experiencing shoulder/back pain at a site she
identifies near the right lower scapula, but
no tenderness can be
elicited during the back and shoulder examination.
Question
3 of 7
Following appropriate
diagnostic studies, the patient is taken to the surgical suite. During the
surgery, the surgeon inserts his fingers from
right to left behind the
hepatoduodenal ligament. As he does so, his fingers enter which of the
following?
/ A. Ampulla of Vater
/ B. Common bile duct
/ C. Epiploic foramen
/ D. Greater peritoneal sac
/ E. Portal vein
|
Explanation - Q: 2.3
|
|
The correct answer is C. The space behind the
stomach, hepatoduodenal ligament, and hepatogastric ligament is the omental
bursa. This space can be entered by passing through the epiploic foramen of
Winslow, as described in the question stem.
The common bile duct enters the duodenum through the
ampulla of Vater (choice A).
The hepatoduodenal ligament contains the common bile
duct (choice B), the portal vein (choice E), and the hepatic
artery.
The greater peritoneal sac (choice D) lies
anterior to the stomach and hepatoduodenal ligament.
|
A 47-year-old woman
presents to the emergency department with cramping/colicky abdominal pain. The
current episode of pain began
several hours ago,
following a fatty meaI. The pain began slowly, and rose in intensity to a
plateau over the course of several hours. The
patient reports that she
had had several other episodes of similar pain during the past several months,
with long intervening periods of
freedom from pain. On
physical examination, she is noted to have tenderness to deep palpation in the
right upper quadrant of the abdomen
near the rib cage. The
patient also reports that she is experiencing shoulder/back pain at a site she
identifies near the right lower scapula, but
no tenderness can be
elicited during the back and shoulder examination.
Question
4 of 7
During the
cholecystectomy, the surgeon ligates the cystic artery. This is typically a
branch of which of the following?
/ A. Gastroduodenal artery
/ B. Left gastroepiploic artery
/ C. Right gastroepiploic artery
/ D. Right hepatic artery
/ E. Superior pancreaticoduodenal artery
|
Explanation - Q: 2.4
|
|
The correct answer is D. The cystic artery is
generally a branch of the right hepatic artery.
The gastroduodenal artery (choice A) is a branch
of the (common) hepatic artery.
The left gastroepiploic artery (choice B) is a
branch of the splenic artery.
The right gastroepiploic artery (choice C) is a
branch of the gastroduodenal artery.
The superior pancreaticoduodenal artery (choice E)
is a branch of the gastroduodenal artery.
|
A 47-year-old woman
presents to the emergency department with cramping/colicky abdominal pain. The
current episode of pain began
several hours ago,
following a fatty meaI. The pain began slowly, and rose in intensity to a
plateau over the course of several hours. The
patient reports that she
had had several other episodes of similar pain during the past several months,
with long intervening periods of
freedom from pain. On
physical examination, she is noted to have tenderness to deep palpation in the
right upper quadrant of the abdomen
near the rib cage. The
patient also reports that she is experiencing shoulder/back pain at a site she
identifies near the right lower scapula, but
no tenderness can be
elicited during the back and shoulder examination.
Question
5 of 7
Pathologic examination of
the specimen removed by the surgeon demonstrates the presence of numerous
yellow stones (shown above).
These are most likely
composed primarily of which of the following?
/ A. Bilirubinate
/ B. Calcium phosphate
/ C. Cholesterol
/ D. Cystine
/ E. Struvite
|
Explanation - Q: 2.5
|
|
The correct answer is C. The stones are gallstones,
and their yellow color indicates that they are composed of cholesterol.
Cholesterol stones are the most common form of gallstones. Risk factors
include female sex, multiparity, obesity, increased age (female, fat, forty,
and fertile) and North American Indian race.
Bilirubinate (choice A) gallstones, which are
usually associated with hemolytic anemias, are less common, brown, rather
than yellow, and often faceted.
Calcium phosphate (choice B), cystine (choice
D), and struvite (choice E) composition can be seen in kidney
stones.
|
A 47-year-old woman
presents to the emergency department with cramping/colicky abdominal pain. The
current episode of pain began
several hours ago,
following a fatty meaI. The pain began slowly, and rose in intensity to a
plateau over the course of several hours. The
patient reports that she
had had several other episodes of similar pain during the past several months,
with long intervening periods of
freedom from pain. On
physical examination, she is noted to have tenderness to deep palpation in the
right upper quadrant of the abdomen
near the rib cage. The
patient also reports that she is experiencing shoulder/back pain at a site she
identifies near the right lower scapula, but
no tenderness can be
elicited during the back and shoulder examination.
Question
6 of 7
If this patient had a
small stone lodge near the ampulla of Vater, which of the following
complications would be most likely to occur?
/ A. Crohn disease
/ B. Diabetes mellitus
/ C. Pancreatitis
/ D. Peptic ulcer
/ E. Polyarteritis nodosa
|
Explanation - Q: 2.6
|
|
The correct answer is C. A small gallstone
obstructing the pancreatic outflow is a well-known cause of acute
pancreatitis. The other conditions listed are not caused by gallstones.
|
A 47-year-old woman
presents to the emergency department with cramping/colicky abdominal pain. The
current episode of pain began
several hours ago,
following a fatty meaI. The pain began slowly, and rose in intensity to a plateau
over the course of several hours. The
patient reports that she
had had several other episodes of similar pain during the past several months,
with long intervening periods of
freedom from pain. On
physical examination, she is noted to have tenderness to deep palpation in the
right upper quadrant of the abdomen
near the rib cage. The
patient also reports that she is experiencing shoulder/back pain at a site she
identifies near the right lower scapula, but
no tenderness can be
elicited during the back and shoulder examination.
Question
7 of 7
If this patient had
refused surgical treatment, which of the following would be the most
appropriate pharmacotherapy to provide definitive
treatment and thereby
relieve associated pain?
/ A. Ampicillin
/ B. CIofibrate
/ C. Meperidine
/ D. Oxycodone
/ E. Ursodiol
|
Explanation - Q: 2.7
|
|
The correct answer is E. The question is asking,
"Which of the following will eradicate a gallstone?" When a
gallstone is eliminated the pain will subsequently be eliminated. This
question is NOT asking, "which of the following is the most appropriate
form of pain control?". Ursodiol (ursodeoxycholic acid) is a hydrophilic
bile acid that is used to dissolve small (< 20 mm), non-calcified,
radiolucent cholesterol gallstones in patients with functioning gallbladders
who cannot undergo (or refuse) cholecystectomy.
Analgesics and antibiotics, such as ampicillin (choice
A), are administered when appropriate, but do not help eradicate the stones.
Clofibrate (choice B) is an antihyperlipidemic
that is associated with the development of gallstones. High-risk patients,
such as diabetics and the elderly, should be watched closely.
As a side note, if this question were asking:
"which of the following is the most appropriate form of pain control in
this patient", the most appropriate answer would be meperidine.
Meperidine (choice C) is the narcotic of choice since it causes the
least amount of spasm of the sphincter of Oddi. In other words, meperidine is
preferred over oxycodone (choice D).
|
A 64-year-old man with a
history of coronary artery disease (CAD) comes to the emergency department with
the acute onset of severe,
constant, Iower abdominal
pain and rectal bleeding. He reports that he previously has had several
episodes of similar, but less severe pain.
About 12 hours after the
onset of pain, the patient began passing copious bright red blood per rectum.
He denies nausea, vomiting, sick
contacts, or foreign
traveI. Initial physical examination reveals a distressed man, who is afebrile,
but tachypneic, with scant diffuse abdominal
tenderness to palpation.
Rectal examination is positive for blood. Laboratory studies reveal a metabolic
acidosis with an elevated serum
Iactate.
Question
1 of 5
Which of the following is
the most likely diagnosis?
/ A. Colon carcinoma
/ B. Infectious colitis
/ C. Inflammatory bowel disease
/ D. Ischemic colitis
/ E. Necrotizing enterocolitis
|
Explanation - Q: 3.1
|
|
The correct answer is D. A patient with severe
abdominal pain and rectal bleeding with an unremarkable physical examination
is likely suffering from ischemic colitis. "Pain out-of-proportion to
examination" is a classic finding for ischemic colitis. The previous
episodes of less severe pain represent ischemic angina. An infarction has
occurred, as indicated by the rise in serum lactate secondary to the colon's
anaerobic metabolism. The history of coronary artery disease also suggests
this diagnosis, as the atherosclerotic processes that contribute to his CAD
are also likely present in his abdominal vasculature.
Infectious colitis (choice B) is incorrect.
While patients may have bleeding and abdominal pain, nothing in the history
suggests a disease of infectious origin (no sick contacts or foreign travel).
The acute onset also suggests a vascular event, rather than an infectious
one.
Inflammatory bowel disease (IBD) (choice C) is
incorrect because while the patient reports previous episodes, an elderly man
with IBD would likely have a chronic history of abdominal pain and bleeding.
Necrotizing enterocolitis (choice E) affects
premature infants and would not be relevant in this setting.
|
A 64-year-old man with a
history of coronary artery disease (CAD) comes to the emergency department with
the acute onset of severe,
constant, Iower abdominal
pain and rectal bleeding. He reports that he previously has had several
episodes of similar, but less severe pain.
About 12 hours after the
onset of pain, the patient began passing copious bright red blood per rectum.
He denies nausea, vomiting, sick
contacts, or foreign
traveI. Initial physical examination reveals a distressed man, who is afebrile,
but tachypneic, with scant diffuse abdominal
tenderness to palpation.
Rectal examination is positive for blood. Laboratory studies reveal a metabolic
acidosis with an elevated serum
Iactate.
Question
2 of 5
The lactate produced from
the anaerobic metabolism in the infarcted gut will likely be which of the
following?
/ A. Exhaled as a fruity odor
/ B. Incorporated into glycogen in the liver
/ C. Incorporated into myoglobin in muscle
/ D. Incorporated into urea in the urine
/ E. Secreted by the kidneys unchanged
|
Explanation - Q: 3.2
|
|
The correct answer is B. Lactate is converted
into glucose, and then glycogen in the liver by a process know as the Cori
cycle.
Choice A is incorrect, as lactate would not be
exhaled. A fruity odor on the breath would be a sign of ketoacidosis.
While some of the carbon from the lactate may be
incorporated into peptides via Krebs intermediates (e.g., choice C),
the vast majority would be left as carbohydrate.
Urea (choice D) represents a means of eliminating
nitrogenous waste.
Choice E is wrong, as the kidneys would retain
the lactate, rather than excreting it.
|
A 64-year-old man with a
history of coronary artery disease (CAD) comes to the emergency department with
the acute onset of severe,
constant, Iower abdominal
pain and rectal bleeding. He reports that he previously has had several
episodes of similar, but less severe pain.
About 12 hours after the
onset of pain, the patient began passing copious bright red blood per rectum.
He denies nausea, vomiting, sick
contacts, or foreign
traveI. Initial physical examination reveals a distressed man, who is afebrile,
but tachypneic, with scant diffuse abdominal
tenderness to palpation.
Rectal examination is positive for blood. Laboratory studies reveal a metabolic
acidosis with an elevated serum
Iactate.
Question
3 of 5
If this patient's disease
were drug-induced, which of the following agents would most likely be
responsible?
/ A. Acetaminophen
/ B. Amiodarone
/ C. Cocaine
/ D. Dexamethasone
/ E. Nitroglycerin
|
Explanation - Q: 3.3
|
|
The correct answer is C. Cocaine is a
sympathomimetic drug that indirectly acts on both the alpha and beta
adrenergic receptors on the vasculature. As such, cocaine may cause vasospasm
in the abdominal vasculature leading to infarction and ischemic colitis.
Similar vasospastic events may occur in the coronary vasculature, leading to
myocardial infarction.
Acetaminophen (choice A) is an analgesic, and
would not play a role in producing ischemic colitis.
Amiodarone (choice B) is an antiarrhythmic, and
would not contribute to ischemic colitis.
Dexamethasone (choice D) is a steroidal
anti-inflammatory drug. Not only would this medication not cause ischemic
colitis, it might mask the symptoms due to its potent anti-inflammatory
properties.
Nitroglycerin (choice E) is a venodilator, and
would not contribute to ischemic colitis. As a venodilator, nitroglycerin is
used to treat coronary ischemia by reducing cardiac preload.
|
A 64-year-old man with a
history of coronary artery disease (CAD) comes to the emergency department with
the acute onset of severe,
constant, Iower abdominal
pain and rectal bleeding. He reports that he previously has had several episodes
of similar, but less severe pain.
About 12 hours after the
onset of pain, the patient began passing copious bright red blood per rectum.
He denies nausea, vomiting, sick
contacts, or foreign
traveI. Initial physical examination reveals a distressed man, who is afebrile,
but tachypneic, with scant diffuse abdominal
tenderness to palpation.
Rectal examination is positive for blood. Laboratory studies reveal a metabolic
acidosis with an elevated serum
Iactate.
Question
4 of 5
While the patient is in
the emergency department, the pain becomes increasingly severe. Several hours
after his initial examination, the
patient becomes febrile
and is now exquisitely tender to palpation. He writhes in pain when the
physician jostles the bed. Air is seen under
the diaphragm in an
upright chest x-ray film. These new findings suggest which of the following?
/ A. Abdominal aortic aneurysm
/ B. Bowel obstruction
/ C. Cholecystitis
/ D. Hypovolemia
/ E. Perforation with peritonitis
|
Explanation - Q: 3.4
|
|
The correct answer is E. This patient has
experienced a bowel perforation. Air under the diaphragm in an upright chest
film provides definitive evidence that a hollow viscus has ruptured. Air near
the liver on a left lateral decubitus (patient lays with the left side down)
is an alternative study to demonstrate perforation. Spillage from the
perforated bowel has irritated and inflamed the peritoneum, resulting in
peritonitis. Symptoms of peritonitis include extreme, sharp pain exacerbated
by jostling (patients often report that the bumpy ride to the emergency
department caused extreme pain). Patients will be exquisitely tender to
palpation and percussion and may have abdominal rigidity. Fever typically
accompanies peritonitis.
While an abdominal aortic aneurysm or AAA (choice A)
presents as acute abdominal pain, this pain is described as tearing and may
radiate to the back. A pulsatile abdominal mass may be palpated. The air on
the chest film is also inconsistent with AAA.
This patient does not have bowel obstruction (choice
B). Signs and symptoms of bowel obstruction include: nausea, vomiting,
intermittent abdominal pain, hypovolemia, abdominal distention, absence of
flatus, and a "step ladder" bowel pattern on abdominal films.
Cholecystitis (choice C) typically presents as
right upper quadrant (RUQ) pain, fever, and jaundice. Patients usually have a
history of colicky RUQ pain.
While the patient is at risk for hypovolemia (choice
D), none of the symptoms listed typify hypovolemia. Signs and symptoms of
mild to moderate hypovolemia include malaise, dry mouth, thirst, decreased
skin turgor, tachycardia, hypotension, and decreased urine output.
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A 64-year-old man with a
history of coronary artery disease (CAD) comes to the emergency department with
the acute onset of severe,
constant, Iower abdominal
pain and rectal bleeding. He reports that he previously has had several
episodes of similar, but less severe pain.
About 12 hours after the
onset of pain, the patient began passing copious bright red blood per rectum.
He denies nausea, vomiting, sick
contacts, or foreign
traveI. Initial physical examination reveals a distressed man, who is afebrile,
but tachypneic, with scant diffuse abdominal
tenderness to palpation.
Rectal examination is positive for blood. Laboratory studies reveal a metabolic
acidosis with an elevated serum
Iactate.
Question
5 of 5
Upon surgical exploration
of the abdomen, the colon is dull and dusky from the mid transverse colon to
the rectum. The patient has occluded
which of the following
vessels?
/ A. Celiac trunk
/ B. Cystic artery
/ C. External iliac artery
/ D. Inferior mesenteric artery
/ E. Superior mesenteric artery
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Explanation - Q: 3.5
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|
The correct answer is D. The inferior mesenteric
artery distributes blood to the embryologic hindgut. This includes the distal
1/3 of the transverse colon to the rectum. The rectum is spared because it receives
circulation from the inferior rectal artery (not mesenteric).
The celiac trunk (choice A) supplies the
embryologic foregut. The first three branches include the splenic artery, the
left gastric artery, and the common hepatic artery. This patient has no
findings in this distribution.
The cystic artery (choice B) supplies the gall
bladder. There are no gall bladder findings in this case.
The external iliac artery (choice C) gives rise
to the vessels of the lower extremity. Symptoms of occlusion or stenosis
might include buttock and thigh pain exacerbated by walking. Severe stenosis
might give patients buttock and thigh pain, even at rest.
The superior mesenteric artery (choice E)
supplies the embryologic hindgut. This extends from the duodenum to the
proximal 2/3 of the transverse colon.
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A 45-year-old man goes to
an emergency department because he is experiencing severe abdominal pain, which
is radiating straight through
to his back. The pain
began several hours after an admitted alcoholic binge, and has not changed in
position, although it has become worse.
Question
1 of 5
Which of the following
would be the most likely cause of this type of pain?
/ A. Acute appendicitis
/ B. Acute hepatitis
/ C. Acute pancreatitis
/ D. Chronic hepatitis
/ E. Myocardial infarction
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Explanation - Q: 4.1
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|
The correct answer is C. The typical pain
described occurs in approximately 50% of patients with acute pancreatitis.
Other patients may have milder pain or even, uncommonly, pain first felt in
the lower abdomen.
The pain of acute appendicitis (choice A) is
often felt first as referred pain near the umbilicus, with tenderness on
palpation in the left lower quadrant.
Acute hepatitis (choice B) can cause pain referred
to the right shoulder.
Chronic hepatitis (choice D) does not usually
cause pain.
Myocardial infarction (choice E) can cause
substernal pain and pain radiating to the left shoulder.
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A 45-year-old man goes to
an emergency department because he is experiencing severe abdominal pain, which
is radiating straight through
to his back. The pain
began several hours after an admitted alcoholic binge, and has not changed in
position, although it has become worse.
Question
2 of 5
In addition to alcohol
use, which of the following is a common predisposing factor for this patient's
disease?
/ A. Biliary tract stones
/ B. Duodenal cancer
/ C. Gastric carcinoma
/ D. Kidney stones
/ E. Peptic ulcer
|
Explanation - Q: 4.2
|
|
The correct answer is A. The overwhelmingly most
common predisposing factors for acute pancreatitis are gallstones (more
specifically tiny ones that lodge in the extrahepatic bile duct system) and
alcohol abuse.
Rarely, nearby cancers (choices B and C) can
occlude the pancreatic duct system and cause a secondary acute pancreatitis.
Kidney stones (choice D) have no relationship
with pancreatitis.
Peptic ulcers (choice E) that erode into the
pancreas can uncommonly secondarily inflame the pancreas.
|
A 45-year-old man goes to
an emergency department because he is experiencing severe abdominal pain, which
is radiating straight through
to his back. The pain
began several hours after an admitted alcoholic binge, and has not changed in
position, although it has become worse.
Question
3 of 5
Marked serum elevation of
which of the following markers would most strongly substantiate the likely
diagnosis?
/ A. Acid phosphatase
/ B. Amylase
/ C. Aspartate aminotransferase
/ D. AIkaline phosphatase
/ E. Creatinine kinase
|
Explanation - Q: 4.3
|
|
The correct answer is B. The usual markers for
pancreatitis are amylase and lipase. Marked elevation of amylase usually
means either pancreatic disease or salivary gland disease; lipase will be
elevated in pancreatic disease but not salivary gland disease. If you see
elevated amylase on a USMLE question, you should think of pancreatitis or
salivary gland disease (mumps, salivary gland stone). However, you should be
aware, for your general medical knowledge, that modest elevations of amylase
can be seen in a much wider variety of settings (often reflecting either
subclinical pancreatic damage or hemoconcentration of pancreatic enzymes),
including GI obstruction, mesenteric thrombosis and infarction,
macroamylasemia (a genetic condition with abnormal amylase), renal disease,
ruptured tubal pregnancy, lung cancer, acute alcohol ingestion, and following
abdominal surgery.
Associate acid phosphatase (choice A) with
diseases involving the prostate and, to lesser degrees, bone, the heart,
platelets, and the liver.
Associate aspartate aminotransferase (choice C)
with diseases of the heart, muscle, liver, pancreas (though not as important
for diagnosis as amylase and lipase), and brain.
Associate alkaline phosphatase (choice D) with
diseases of bone, liver, and to lesser degrees, lung and heart.
Associate creatinine kinase (choice E) with
diseases of the heart, muscle, brain, and the general body (trauma, surgery).
|
A 45-year-old man goes to
an emergency department because he is experiencing severe abdominal pain, which
is radiating straight through
to his back. The pain
began several hours after an admitted alcoholic binge, and has not changed in
position, although it has become worse.
Question
4 of 5
The patient has a severe
course that requires treatment in an ICU. CIinically, he appears similar to
patients with sepsis, with fever, elevated
white count, hypotension,
increased pulse rate, shallow and rapid breathing, oliguria, and a blunted
sensorium, in addition to his pain and
abdominal tenderness.
These clinical findings are most likely related to which of the following?
/ A. Activation of the inflammatory cascade
/ B. AIcohol withdrawal symptoms
/ C. AIIergic reaction to alcohol
/ D. Drug toxicity effect
/ E. Secondary infection with mixed flora gut bacteria
|
Explanation - Q: 4.4
|
|
The correct answer is A. Acute pancreatitis can
either be relatively mild, or a severe condition that may cause death. It is
thought that, in severe cases, leakage of enzyme-containing pancreatic
secretions into the tissues/and or blood stream causes cleavage of
precursors, thus strongly activating the complement and inflammatory
cascades. These, in turn, produce abundant cytokines, which worsen the
symptoms. The clinical result is similar to sepsis, with risk of multi-organ
failure and death. The treatment of acute pancreatitis is primarily
supportive, and may include careful attention to fluid resuscitation, oxygen
supplementation, cardiovascular support, dialysis, management of electrolyte
abnormalities, pain control, and total parenteral nutrition.
Alcohol allergy (choice C) or withdrawal (choice
B) do not play any additional part in most of these symptoms once the
pancreatitis has developed.
Infection (choice E) and drug toxicity (choice
D) are also not a necessary part of the clinical picture, although
physicians may worry that the patient's general clinical status is masking
other, potentially more treatable, problems.
|
A 45-year-old man goes to
an emergency department because he is experiencing severe abdominal pain, which
is radiating straight through
to his back. The pain began
several hours after an admitted alcoholic binge, and has not changed in
position, although it has become worse.
Question
5 of 5
The patient's condition
resolves in about two weeks, but he continues to drink after leaving the
hospitaI. When seen several years later, he
has had a number of
similar episodes, and now has chronic severe abdominal pain. CT scan
demonstrates a single, smooth-walled, fluid
filled space in the tail
of the pancreas, which can be reached by the radiologist for CT-guided
aspiration with an approach from the back. The
fluid aspirated is
yellowish, clear, and acellular. Which of the following is the most likely
diagnosis?
/ A. Pancreatic microcystic adenoma
/ B. Pancreatic mucinous cystadenocarcinoma
/ C. Pancreatic mucinous cystadenoma
/ D. Pancreatic pseudocyst
/ E. Pancreatic solid-cystic tumor
|
Explanation - Q: 4.5
|
|
The correct answer is D. Pancreatic pseudocyst
is a fairly common complication of both acute and chronic pancreatitis, and
appears to develop when trapping of pancreatic digestive juices (containing
amylase, lipase, and proteases) causes a "digestion" of part of the
pancreas, leaving a fluid filled cystic space. The term
"pseudocyst", rather than "cyst", is used by purists
because the space does not have an epithelial lining, and is hence not a
"true cyst". Pseudocysts are usually solitary and typically measure
5-10 cm in diameter. They can be surgically excised (and the surrounding
tissue will typically show evidence of chronic pancreatitis in long-standing
cases) or sometimes, if the anatomy is favorable, drained into adjacent
hollow viscera. Some are medically managed if small.
Most true neoplasms of the pancreas contain (often
large numbers of) smaller, multiple, cysts. These tumors can be benign or
malignant, and the ones with mucus-secreting epithelium (choices B and C)
are more common than those with a serous lining (choices A and E).
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A 17-year-old boy is taken
to the emergency department because he has developed severe abdominal pain. The
pain began abruptly
several hours previously,
and was felt initially in the periumbilical region, but later shifted to the
right lower quadrant. The boy had initially felt
somewhat nauseous, but
this has passed. On physical examination, he is noted to have localized pain on
cough and to be running a low-
grade fever.
Question
1 of 5
Examination of the abdomen
demonstrates right lower quadrant tenderness at the junction of the middle and
outer thirds of the line joining the
umbilicus to the anterior
superior spine of the iliac. This location is known as which of the following?
/ A. Gubernaculum
/ B. Langer's line
/ C. Linea alba
/ D. McBurney's point
/ E. Tunica albuginea
|
Explanation - Q: 5.1
|
|
The correct answer is D. The point described is
McBurney's point, which overlies the location of the appendix in most
individuals.
The gubernaculum (choice A) is the fibrous cord
that connects the primordial testis or ovary to the anterolateral abdominal
wall.
Langer's lines (choice B) are the cleavage lines
of the skin.
The linea alba (choice C) is a sheet-like
aponeurosis that covers the anterior abdominal wall.
The tunica albuginea (choice E) is a tough
fibrous coat that covers the testis.
|
A 17-year-old boy is taken
to the emergency department because he has developed severe abdominal pain. The
pain began abruptly
several hours previously,
and was felt initially in the periumbilical region, but later shifted to the
right lower quadrant. The boy had initially felt
somewhat nauseous, but
this has passed. On physical examination, he is noted to have localized pain on
cough and to be running a low-
grade fever.
Question
2 of 5
Which of the following is
the most likely diagnosis?
/ A. Appendicitis
/ B. Diverticulitis
/ C. Gallstones
/ D. Rectal ulcer
/ E. Renal colic
|
Explanation - Q: 5.2
|
|
The correct answer is A. This patient has a
typical presentation for appendicitis, and the diagnosis is confirmed by the
presence of localized tenderness at McBurney's point.
Diverticulitis (choice B) is usually a disease
of middle-aged or older individuals and most commonly affects the left-lower
quadrant.
Symptomatic gallstone disease (choice C) causes
pain and tenderness in the right upper quadrant.
Rectal ulcer (choice D) causes pain with stool
movement, but does not usually produce tenderness identifiable on abdominal
examination.
Renal colic (choice E) usually produces flank or
lower back pain.
|
A 17-year-old boy is taken
to the emergency department because he has developed severe abdominal pain. The
pain began abruptly
several hours previously,
and was felt initially in the periumbilical region, but later shifted to the
right lower quadrant. The boy had initially felt
somewhat nauseous, but
this has passed. On physical examination, he is noted to have localized pain on
cough and to be running a low-
grade fever.
Question
3 of 5
The patient also exhibits
an increase in pain in the right lower quadrant from the passive extension of
the right hip joint. This finding suggests
that the inflammation also
involves which of the following?
/ A. BIadder
/ B. External oblique muscle
/ C. Femur
/ D. IIiopsoas muscle
/ E. Transverse abdominal muscle
Explanation - Q: 5.3
|
|
The correct answer is D. This patient has a
"positive psoas sign," which is an increase in pain from passive
extension of the right hip joint. This maneuver stretches the iliopsoas
muscle, which lies behind the appendix and can become secondarily inflamed
when the appendiceal inflammation extends through the serosa. The psoas sign
is clinically useful in both confirming the appendix as the probable origin
of the patient's pain, and indicating that the inflammation is transmural and
that the risk of rupture and peritonitis is increased.
The bladder (choice A) is located more medially,
and is usually not affected by appendicitis.
The external oblique (choice B) and transverse
abdominal (choice E) muscles are in the anterior and lateral abdominal
walls, and do not usually become inflamed with appendicitis.
The femur (choice C) is moved during the
extension of the right hip joint, but is not the source of the pain.
|
A 17-year-old boy is taken
to the emergency department because he has developed severe abdominal pain. The
pain began abruptly
several hours previously,
and was felt initially in the periumbilical region, but later shifted to the
right lower quadrant. The boy had initially felt
somewhat nauseous, but
this has passed. On physical examination, he is noted to have localized pain on
cough and to be running a low-
grade fever.
Question
4 of 5
The patient is prepared
for immediate surgery. Cefotaxime is administered before, during, and after
surgery. The specimen, once removed,
is sent to the laboratory
for pathology and bacteriologic culture. A malodorous pus surrounds the serosa
of the surgical specimen, and a
mixed gram-negative flora
is cultured. Rapid enzyme tests for beta-Iactamase production are positive.
Which of the following drugs should be
added to the initial
cefotaxime regimen?
/ A. Bacitracin
/ B. CIavulanic acid
/ C. CIindamycin
/ D. Isoniazid
/ E. Vancomycin
|
Explanation - Q: 5.4
|
|
The correct answer is B. Clavulanic acid is a
beta-lactamase inhibitor, which when administered with beta lactam agents,
irreversibly binds and inactivates bacterial beta-lactamases, thereby
permitting the companion drug to disrupt bacterial cell wall synthesis.
Suspected appendicitis is usually treated with prompt appendectomy, since
delay is associated with increased risk of potentially life-threatening
peritonitis and sepsis.
Bacitracin (choice A) is not correct, since this
drug inhibits bacterial cell wall synthesis by binding to and inhibiting the
dephosphorylation of a membrane-bound lipid pyrophosphate. Gram-negative
bacteria are resistant to this agent, and it would not have a synergistic
effect if administered with a third generation cephalosporin.
Clindamycin (choice C) is not correct, because
this drug blocks protein elongation by binding to the 50S ribosome. Although
it is effective against anaerobic gram-negative bacilli, it would not have a
complementary effect when administered with a third generation cephalosporin.
Isoniazid (choice D) is not correct because it
inhibits the synthesis of mycolic acids for the cell wall of actively
dividing Mycobacteria. It would not be effective in the flora of this
patient's gut, nor would it act synergistically with third generation
cephalosporins.
Vancomycin (choice E) is not correct because it
disrupts cell wall synthesis in growing gram-positive bacteria. It would not
be effective against the flora of this patient's gut, nor would it act synergistically
with third generation cephalosporins.
|
A 17-year-old boy is taken
to the emergency department because he has developed severe abdominal pain. The
pain began abruptly
several hours previously,
and was felt initially in the periumbilical region, but later shifted to the
right lower quadrant. The boy had initially felt
somewhat nauseous, but
this has passed. On physical examination, he is noted to have localized pain on
cough and to be running a low-
grade fever.
Question
5 of 5
The patient's
postoperative recovery is uneventfuI, but 10 days after discharge, he returns
to his physician complaining of continuous low-
grade fever. An abscess is
drained transrectally, and
organisms are cultured from the pus. Which of the following is an
attribute of
this organism that makes
it an important abscess former?
/ A. It is an anaerobe
/ B. It is an intracellular pathogen
/ C. Its endotoxin lacks 2,3-ketodeoxyoctonate
/ D. Mycolic acid
/ E. Prodigious capsule
|
Explanation - Q: 5.5
|
|
The correct answer is E. Prevotella
(Bacteroides) is a frequent cause of abscesses in the intestinal tract
because it is a normal flora organism and produces a large capsule, which
impedes phagocytosis.
Although the genus is anaerobic (choice A), it
is not this attribute which causes its formation of abscesses.
Prevotella is extracellular, not an
intracellular pathogen (choice B).
Although Prevotella does indeed have this type
of endotoxin (choice C), the absence of this molecule decreases the
toxicity of the toxin, and does not contribute to its proclivity toward
abscess formation.
Mycobacteria, and not other genera such as Prevotella,
are known for their long-chain fatty acids (mycolic acids; choice D).
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