Unusual Cause of Acute Stroke in a Young Woman with Patent Foramen Ovale - Duplicated Inferior Vena Cava and May-Thurner Syndrome.

The etiology of acute ischemic stroke (AIS) may often remain uncertain despite diligent work-up, especially in young people. Although patent foramen ovale (PFO) is a frequent association during such work-up, the actual source of thromboembolism, like deep vein thrombosis (DVT), may not be found. Such associative pathology makes it challenging to prescribe anticoagulation for secondary stroke prevention. We describe a young woman with a known history of PFO who presented with AIS and underwent endovascular reperfusion therapy. Post-thrombectomy, she developed hypoxic respiratory failure due to pulmonary embolism. Initiation of therapeutic anticoagulation was complicated by a retroperitoneal bleed necessitating imaging studies for etiological work-up. Computed tomographic angiography and venogram showed no active contrast extravasation but demonstrated duplication of the inferior vena cava with DVT in the right iliofemoral vein (RIFV). The proximity of the right common iliac artery compressing RIFV against the pelvic inlet is described as May-Thurner syndrome (MTS). Afterward, the patient was successfully treated with anticoagulation and PFO closure. MTS is a rare and underdiagnosed cause of iliofemoral DVT. In patients with known PFO, MTS is a possible cause that needs consideration. Hence, appropriate diagnostic tests are necessary to initiate appropriate management and to prevent AIS recurrence.