Coagulation Disorders USMLE Step 1 Practice Question
A 34-year-old woman presents to her primary care physician with a 20-year history of heavy menstrual bleeding requiring iron supplementation and occasional transfusion. She reports frequent spontaneous bruising on her extremities and a 2-day episode of epistaxis 6 months ago. She denies joint pain or swelling. She takes no medications including anticoagulants or antiplatelet agents. Her mother had similar menstrual bleeding requiring hysterectomy at age 42. Vital signs are within normal limits. Physical examination reveals mild pallor but no hepatosplenomegaly or lymphadenopathy. Laboratory evaluation shows: hemoglobin 9.8 g/dL, platelets 248,000/μL, PT 13 seconds, aPTT 52 seconds, fibrinogen 310 mg/dL. A mixing study is performed by incubating patient plasma 1:1 with normal pooled plasma, and the aPTT normalizes to 32 seconds. The bleeding time is normal. Which of the following is the most likely diagnosis?
Answer choices
- AHemophilia A (Factor VIII deficiency)Correct answer
- BHemophilia B (Factor IX deficiency)
- CVitamin K deficiency
- DVon Willebrand disease
- EFactor II deficiency
- FLupus anticoagulant
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