Vascular Disease USMLE Step 1 Practice Question
A 38-year-old woman with a 15-year history of migraine with aura presents to the emergency department with acute-onset left leg swelling, calf pain, and warmth that began this morning. She initiated smoking 3 months ago and has been on combined oral contraceptives for 2 years. Vital signs are stable with BP 128/82, HR 92, RR 16, temp 37.2°C, and SpO2 98% on room air. Physical examination reveals unilateral lower extremity edema with palpable warmth over the calf. Compression ultrasonography demonstrates absence of compressibility in the left popliteal vein with echogenic thrombus. D-dimer is elevated at 2.8 μg/mL. Chest examination is unremarkable and pulse oximetry remains normal. Which of the following is the primary modifiable risk factor contributing to her venous thromboembolism?
Answer choices
- AMigraine with aura, which causes recurrent transient hypercoagulability through platelet activation
- BCombined oral contraceptive use, which increases risk through estrogen-mediated changes in coagulation factorsCorrect answer
- CSmoking within 3 months of presentation, which impairs endothelial function and platelet adhesion
- DRecent immobilization from prolonged sitting related to work or travel during thrombosis development
- EUnderlying inherited thrombophilia such as Factor V Leiden, which is unmasked by oral contraceptive use
- FCompression of the popliteal vein from Baker's cyst or other anatomical variant
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