The Question
A 42-year-old woman is evaluated 10 days after a first unprovoked proximal deep vein thrombosis of the left leg, confirmed by compression ultrasonography. She has no prior thrombosis, no recent surgery, travel, estrogen use, or pregnancy. Her mother had a pulmonary embolism at age 48. She is taking apixaban and feels well. Hemoglobin, platelet count, creatinine, and liver tests are normal. She asks whether she should undergo blood testing now to determine if she has an inherited clotting disorder and whether that would change treatment. Which of the following is the most appropriate next step in management?
See the answer and explanation below:
Post-Call Recovery Reads
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View on AmazonThe Correct Answer
B
Explanation
Clinical Pearl:
Routine inherited thrombophilia testing rarely changes management after a first unprovoked venous thromboembolism and should not be sent during acute thrombosis or while a patient is taking a direct oral anticoagulant.
Explanation:
This patient has a first unprovoked proximal DVT, for which guideline-based care is therapeutic anticoagulation for at least 3 months, with later reassessment of bleeding risk and the value of extended therapy. Routine inherited thrombophilia testing is usually not recommended because results seldom alter immediate treatment duration and can be misleading in the acute setting. Protein C, protein S, and antithrombin levels may be affected by the thrombotic event and by anticoagulants, so sending them now would not provide reliable guidance. Stopping anticoagulation at 6 weeks is substandard for proximal DVT, even if testing were negative. Switching to warfarin is unnecessary because a direct oral anticoagulant is appropriate first-line therapy for most noncancer-associated VTE, and an inferior vena cava filter is reserved for patients who cannot receive anticoagulation or who have recurrent embolism despite it.
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