Kaplan USMLE Step 3: 70-year-old man has gastrointestinal bleeding

If you’re preparing for the United States Medical Licensing Examination® (USMLE®) Step 3 exam, you might want to know which questions are most often missed by test-prep takers. Check out this example from Kaplan Medical, and read an expert explanation of the answer. Also check out all posts in this series.

A 70-year-old man comes to the emergency department after seeing bright red blood in the toilet bowl. Initially, he assumed the problem was hemorrhoids or something he ate and that it would pass. He then had three to four additional episodes of painless hematochezia. In the emergency department, the patient is found to have orthostatic hypotension, mild tachycardia and a hematocrit of 21%. The patient is stabilized and transfused with three units of packed red blood cells, and the bleeding spontaneously stops. The next morning, the patient undergoes a colonoscopy that reveals multiple ectatic, dilated, thin-walled vessels throughout the colon. Which of the following is the most likely associated finding given this patient's cause of gastrointestinal bleeding?

A. A crescendo-decrescendo murmur that radiates to the carotids

B. An elevated prothrombin time, low albumin level, and low cholesterol level

C. Large cystic malformations in the kidneys and cerebral blood vessels

D. The presence of a positive radiolabeled carbon urea breath test

E. The presence of large numbers of gastric and small intestinal polyps

The correct answer is A.

Angiodysplasia, a common cause of gastrointestinal bleeding, is associated with a variety of conditions, including end-stage renal disease, von Willebrand disease, and aortic stenosis. Although these associations with angiodysplasia are well known and well tested, most patients with angiodysplasia do not have any associated condition, aside from advanced age. Aortic stenosis is believed to contribute to angiodysplasia by creating a functional von Willebrand disease (mechanical trauma to the von Willebrand multimers) or perhaps by increasing the likelihood of ischemic necrosis from reduced cardiac output.

Choice B. Liver failure, which can manifest as an elevated prothrombin time, low albumin level and low cholesterol level, is not associated with angiodysplasia. Renal failure, however, is associated with angiodysplasia.