Extensive Left Lower Limb Deep Vein Thrombosis Secondary to May-Thurner Syndrome in a Young Female.

Deep vein thrombosis (DVT) in young adults is uncommon and warrants a thorough workup for hereditary and acquired thrombophilia prior to attributing causation to anatomic factors. May-Thurner syndrome (MTS), an anatomical variant involving compression of the left common iliac vein by the right common iliac artery, results in venous stasis and predisposes to thrombosis. We report a case of a young woman with hemoglobin D-Punjab trait who developed progressive left-leg swelling after multiple long-haul flights between Australia, Bali, and the United Kingdom. She initially underwent assessment for infection-related causes, including cellulitis and Salmonella gastroenteritis. Initial Doppler ultrasound did not demonstrate thrombosis despite high D-dimer, but a subsequent Doppler revealed an extensive thrombosis from the popliteal vein to the common iliac vein. Computed tomography (CT) venography confirmed iliac vein compression consistent with MTS. She received anticoagulation and was evaluated by haematology and vascular teams for thrombolysis and stenting. This case highlights the importance of maintaining suspicion for MTS in unilateral, left-sided DVT, particularly in young women with multiple risk factors, and underscores the importance of repeat imaging when symptoms persist.