May-Thurner Syndrome: A Rare Cause of Deep Venous Thrombosis

Abstract

LEARNING OBJECTIVE #1: To consider rare causes of Deep Venous Thrombosis such as May-Thurner Syndrome in young patients with no identifiable etiology LEARNING OBJECTIVE #2: To recognize the role of stent placement as a means of treating May-Thurner Syndrome CASE: A 20-year-old female presented to the hospital with left lower extremity pain and swelling for 1 week. The swelling was initially in her foot and traveled up to her thigh, and the pain made her unable to ambulate. She denied any recent immobilization, travel or limb trauma. She reported oral contraceptive use and history of smoking one cigarette daily each for the past 1 year. She denied any history of blood clots and her family history was insignificant. She had stable vital signs. On exam, she had unilateral pitting edema in her left lower extremity up to the thigh, and tenderness to palpation in left posterior leg. D-Dimer was elevated at 7.2. Her coagulation profile and other tests for hereditary thrombotic disorders were normal. Ultrasound venous duplex identified a blood clot from the calf extending cephalad proximal to the femoral head, confirming the presence of DVT. She was started on anticoagulation with therapeutic enoxaparin. To prevent clot embolization, inferior vena cava filter (IVC) was placed. Moreover, tissue plasminogen activator was infused through a catheter in the left iliac vein. However, her pain persisted. CT angiogram showed extensive thrombus within the left common iliac vein, left external iliac vein and left femoral vein. There was also found to be narrowing in the distal aspect of left common iliac vein secondary to compression from a crossing left common iliac artery. This suggested the diagnosis of a variant of May-Thurner Syndrome. She underwent placement of stents in left common iliac vein and left iliac vein at level of pelvic rim. Eventually, her symptoms of pain and swelling resolved with the preceding interventions. Her IVC filter was removed, and she was started on warfarin. Once cinically stable, she was discharged with follow up arranged with her hematologist. DISCUSSION: May-Thurner syndrome is a rare condition usually involving compression of the left common iliac vein by the overlying right common iliac artery, however, other variants like the one in our patient also exist. This can result in stasis of blood, leading to thrombosis. Vascular ultrasound or CT angiogram are used to establish the diagnosis. Treatment is based on angioplasty and stenting of iliac vein. Our case demonstrates that one should consider rare causes of DVT such as May-Thurner syndrome in young patients with no other identifiable causes. Thorough investigation and imaging can help identify the condition, and hence, prevent re-thrombosis in such patients.