Coagulation Disorders USMLE Step 1 Practice Question
A 47-year-old man with recurrent deep venous thromboses is started on warfarin monotherapy without bridging heparin. Two days later, he develops painful purpuric skin lesions on his lower extremities that progress to necrosis. Vital signs show BP 128/82, HR 92, RR 16, temperature 37.2°C. PT is markedly elevated at 18 seconds; activated protein C level is low. He denies recent antibiotics or malignancy. Which of the following best explains this complication?
Answer choices
- AEarly depletion of protein C creates a transient hypercoagulable stateCorrect answer
- BExcess platelet activation from antibodies to platelet factor 4
- CInhibition of thromboxane A2 synthesis in platelets
- DDirect autoimmune destruction of dermal blood vessels
- EFibrinogen consumption due to systemic tissue factor release
- FWarfarin-induced inhibition of vitamin K-dependent factors II and VII leading to unopposed thrombin generation
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.