Deep Vein Thrombosis Secondary to Extrinsic Compression: A Case Report

May-Thurner syndrome (MTS) is defined as extrinsic venous compression by the arteries of the iliocaval system. The most common manifestation of MTS is compression of the left common iliac vein by the right common iliac artery. May-Thurner syndrome is pathologically seen in 2%-5% of patients presenting with symptomatic deep vein thrombosis (DVT). As an anatomic variant, the prevalence is predicted to be much higher as most patients with MTS anatomy are asymptomatic and do not seek evaluation.  Symptomatic clinical presentations can include left lower extremity pain, swelling, skin discoloration, ulceration, and venous claudication. Here we present a patient with symptomatic MTS. A 64-year-old female with no pertinent past medical history presented with complaint of worsening left lower extremity swelling and pain. Clinical picture was concerning for phlegmasia cerulea dolens and ultrasound was bypassed in favor of a CT scan of the lower extremities bilaterally. The CT showed occlusion of the deep veins of the left leg secondary to stenosis of the left common iliac vein just posterior to the right common iliac artery; a finding consistent with MTS. Interventional radiology performed a catheter-directed thrombolysis with stenting of the left common iliac and external iliac veins. The patient clinically improved and was discharged with anticoagulative therapy.  May-Thurner syndrome is a condition that typically manifests due to external anatomic compression of the left common iliac vein. It is our belief that patients (with the appropriate risk factors) presenting with signs and symptoms consistent with proximal lower extremity DVT would benefit from further radiographic studies to fully evaluate for iliocaval venous stenosis and subsequent catheter-directed thrombolysis with endovascular stenting.