Coagulation Disorders USMLE Step 1 Practice Question
A 28-year-old woman presents to the emergency department with acute abdominal pain and leg swelling. She reports two unexplained pregnancy losses in the past year and was hospitalized 18 months ago for a left lower extremity deep vein thrombosis. Vital signs are stable. Laboratory evaluation reveals a prolonged activated partial thromboplastin time (aPTT) that does not correct when normal plasma is added to the patient's plasma (mixing study). Serum anticardiolipin antibodies and lupus anticoagulant are both positive. CT angiography confirms acute mesenteric venous thrombosis. Which of the following additional laboratory findings is most consistent with this patient's diagnosis?
Answer choices
- AElevated factor VIII activity
- BThrombocytopenia with fragmented red blood cells on blood smear
- CMarkedly elevated D-dimer with normal fibrinogen
- DPositive direct Coombs test with elevated indirect bilirubin
- ENormal prothrombin time with normal protein C levelCorrect answer
- FProlonged thrombin time with hypofibrinogenemia
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