If you’re preparing for the United States Medical Licensing Examination® (USMLE®) Step 2 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 75-year-old woman with a past medical history significant for paroxysmal atrial fibrillation, hypertension and osteoarthritis comes to the emergency department with bright red blood per rectum. Her medications include warfarin, nifedipine, metoprolol and ibuprofen as needed. She reports that the first incident occurred the previous night, approximately 12 hours earlier, with three subsequent episodes. She denies chest pain, lightheadedness, shortness of breath and abdominal pain. Her temperature is 37.5°C (99.5°F), pulse is 110/minute, respirations are 14/min and blood pressure is 101/72 mm Hg. Abdominal examination is unremarkable, but rectal examination is notable for frank heme-positive stool without palpable masses or hemorrhoids. Laboratory studies show a serum potassium level of 3.1 mEq/L, creatinine 1.4 mg/dL, hemoglobin 6.7 g/dL and INR of 8.5. Which of the following is the best option to reverse her coagulopathy?
A. Activated factor VII
B. Cryoprecipitate
C. Fresh frozen plasma
D. Phytonadione (Vitamin K)
E. Protamine sulfate
The correct answer is C.
Kaplan Medical explains why
Warfarin causes inhibition of the Vitamin K-dependent clotting factors (II, VII, IX, and X, protein C and S). Fresh frozen plasma contains these factors and is the fastest way to reverse coagulopathy caused by warfarin.
Why the other answers are wrong
Choice A. Activated Factor VII has been approved for use in bleeding, but its limited testing and high expense limits its use to critical patients, typically in disseminated intravascular coagulopathy in the operating room.
