May-Thurner syndrome (MTS) involves iliocaval venous compression most often attributed to compression of the left iliac vein between the lumbar vertebrae posteriorly and the right common iliac artery anteriorly. This, in turn, causes venous hypertension and stasis in the left leg. Risk factors include scoliosis (more accentuated compression of the venous system), dehydration, hypercoagulable states (pharmacologic, hereditary, etc.), radiation exposure, and the female gender (especially on OCPs). Therefore, a “textbook vignette” for MTS is a young woman presenting with left leg swelling for weeks.
Workup of MTS involves assessing for flow through the venous system (duplex ultrasound, CT/MR venography) looking for clots and identifying collateral vessels. Most importantly, having a high degree of clinical suspicion in the “right patient” helps tremendously. Treatment varies from compression stockings and angioplasty in cases without DVTs to full anticoagulation and even lytic therapies/thrombectomies in those with preexisting clots.
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