Coagulation Disorders USMLE Step 1 Practice Question
A 68-year-old man with metastatic pancreatic cancer presents to the emergency department with acute onset bilateral leg swelling, dyspnea, and right-sided chest pain. Vital signs: BP 118/76 mmHg, HR 102 bpm, RR 22/min, SpO2 89% on room air. Physical examination reveals petechiae on lower extremities and mild hepatomegaly. Laboratory studies: platelet count 45,000/µL (reference 150,000-400,000), PT 18 seconds (reference 11-13.5), aPTT 58 seconds (reference 25-35), fibrinogen 78 mg/dL (reference 200-400), D-dimer 8.5 µg/mL (reference <0.5), hemoglobin 8.2 g/dL. Blood smear shows schistocytes. Chest CT confirms acute pulmonary embolism. PT remains prolonged despite administration of vitamin K 10 mg IV. Which of the following best explains this clinical presentation?
Answer choices
- AHeparin-induced thrombocytopenia with thrombosis
- BVitamin K deficiency from malabsorption
- CDisseminated intravascular coagulation secondary to malignancyCorrect answer
- DPrimary antithrombin III deficiency
- EThrombotic thrombocytopenic purpura
- FFactor V Leiden heterozygosity with acquired protein C deficiency
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