Coagulation Disorders USMLE Step 1 Practice Question
A 3-year-old boy is brought to the emergency department by his mother after spontaneous epistaxis lasting 2 hours. She reports he had prolonged bleeding for 5 days following circumcision at 2 months of age. She also mentions her brother required multiple transfusions during dental work as a child. Vital signs are stable. Laboratory evaluation shows: platelet count 245,000/μL, PT 13 seconds (normal), aPTT 62 seconds (normal control 28-36 seconds). A mixing study with normal plasma does not correct the aPTT to normal. Assay results show factor VIII activity <1%, von Willebrand factor antigen normal, and fibrinogen 320 mg/dL. Which of the following is the most likely diagnosis?
Answer choices
- AHemophilia ACorrect answer
- BHemophilia B (Factor IX deficiency)
- Cvon Willebrand disease Type 1
- DFactor XI deficiency
- EAntiphospholipid syndrome
- FVitamin K deficiency
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