Coagulation Disorders USMLE Step 1 Practice Question
A 45-year-old man with hemophilia A is scheduled for elective total abdominal colectomy for adenocarcinoma. He has a baseline factor VIII activity of 12% and reports good compliance with home factor VIII infusions. Vital signs are stable. Laboratory values show: activated partial thromboplastin time (aPTT) 64 seconds (reference 25-35), platelet count 248,000/μL, prothrombin time 13 seconds (reference 11-13.5), and fibrinogen 340 mg/dL. He has had no spontaneous bleeding in the past year. The anesthesia and surgical teams ask the hematology service for perioperative factor VIII replacement recommendations. Which of the following target factor VIII levels should be achieved preoperatively and maintained throughout the procedure?
Answer choices
- A20-30% factor VIII activity
- B40-50% factor VIII activity
- C80-100% factor VIII activityCorrect answer
- D10-15% factor VIII activity
- E60-70% factor VIII activity
- F100-120% factor VIII activity
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.