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A 57-year-old postmenopausal woman presented to our emergency department with a 1-day history of left leg pain, redness, and swelling. She reported no chest pain or shortness of breath. During the previous week, she made several car trips, each lasting 3 hours. Her medical history was remarkable for a left femoral and popliteal deep venous thrombosis (DVT) after breast reduction surgery during the previous year, which was treated with 1 week of subcutaneous low-molecular-weight heparin therapy and 6 months of oral warfarin therapy. She also had a history of hyperlipidemia, allergies, gastroesophageal reflux, and depression. She denied using tobacco or illicit drugs. Breast, cervical, and colon cancer screening were current and unremarkable. Daily oral medications were atorvastatin, sertraline, montelukast, and pantoprazole. She reported no family history of DVT.
On arrival at the emergency department, the patient's vital signs were as follows: temperature, 36.8°C; blood pressure, 150/77 mm Hg; heart rate, 71 beats/min; respiratory rate, 18 breaths/min; and room air oxygen saturation, 93%. Physical examination revealed erythema, warmth, tenderness, and swelling of the entire left leg with intact distal pulses (Figure 1). The right leg was unaffected. Laboratory tests revealed the following: white blood cell count, 9.3 × 109/L; hemoglobin, 14.7 g/dL; platelets, 321 × 109/L; creatinine, 0.7 mg/dL; activated partial thromboplastin time, 23 seconds; and international normalized ratio, 0.9.
In 1957, May and Thurner9 reported that 22% of the 430 cadavers examined in their study had obstructive lesions within the left iliac vein owing to chronic endothelial injury caused by compression of the vein by the overlying pulsating right iliac artery and underlying lumbar vertebrae. They speculated that persons with this anatomic configuration were predisposed to DVT. Indeed, left-leg DVT is 3 to 8 times more common than right-leg DVT.
May-Thurner syndrome affects women more than men.15 Patients with this syndrome commonly present with left-leg DVT but may also present with left-leg pain, edema, and venous insufficiency in the absence of DVT.5 Nearly 50% of patients with left iliofemoral DVT have May-Thurner syndrome.16
Iliofemoral DVT usually occurs in the setting of an underlying anatomic configuration that affects the inferior vena cava or iliofemoral veins, such as May-Thurner syndrome, presence of a pelvic mass, or pregnancy.15 Despite adequate anticoagulation, most iliofemoral thromboses do not completely recanalize, resulting in postthrombotic syndrome. As a result, endovascular treatment has emerged as an effective treatment for acute iliofemoral DVT.11 The 2008 American College of Chest Physicians guidelines recommend catheter-directed pharmacothrombolysis, mechanical thrombectomy, and stent placement or surgical thrombectomy in patients with iliofemoral DVT.6
In patients with iliofemoral DVT in the setting of May-Thurner syndrome who have undergone thrombus removal and stent placement, the ideal duration of warfarin anticoagulation is unclear. Guidelines recommend that patients with a transient risk factor for DVT, such as major surgery, be treated for 3 months. Patients with unprovoked DVT should be treated for a minimum of 3 months and then the risks vs benefits of long-term anticoagulation should be evaluated. Patients with a second unprovoked DVT should be treated indefinitely.6 Our patient was predisposed to DVT because of May-Thurner syndrome, and this abnormal anatomic configuration was corrected. Guidelines do not address duration of anticoagulation therapy for this specific scenario. We chose to treat this patient with warfarin anticoagulation for at least 3 months, after which her status was to be reviewed and the need for longer-term or even indefinite anticoagulation therapy was to be considered.
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Correct answers: 1. a, 2. b, 3. e, 4. e, 5. a