May-Thurner Syndrome: a case of unilateral left lower limb deep vein thrombosis

The May–Thurner Syndrome (MTS) is a rare anatomical condition in which the compression of the left common iliac vein by the right common iliac artery causes an outflow obstruction, presenting frequently as chronic venous insufficiency or deep venous thrombosis (DVT). This variant is rarely considered when investigating DVT, especially in patients with other risk factors. MTS requires careful workup and management to avoid complications such as chronic venous insufficiency, post-thrombotic syndrome, and primary lymphedema. The authors present a 63-year-old woman admitted to the emergency department with a 24-hour history of left lower limb pain and edema. Initial assessment, with computed tomography of the lower left limb and pelvis, showed compression of the left common iliac vein with an extensive thrombus of the left common iliac and external iliac veins, as well as femoral and popliteal left veins, consistent with MTS. Therapeutic enoxaparin initially implemented, was then switched to oral anticoagulation. At 6 months reevaluation, venous duplex ultrasound showed only partial recanalization of the femoral vein. Investigation for May-Thurner Syndrome in patients with left lower limb venous thrombotic events, regardless of risk factors, should always be present since the establishment of an effective therapeutic plan and eventually, endovascular treatment can minimize the long-term sequelae of deep vein thrombosis.