Staged Endovascular Management of May–Thurner Syndrome Caused by a Mycotic Right Common Iliac Artery Aneurysm: A Case Report

Objective May–Thurner syndrome (MTS) usually results from compression of the left common iliac vein (LCIV) between the right common iliac artery (RCIA) and vertebral body. Aneurysmal arterial causes are rare, and a mycotic RCIA aneurysm is exceptional. This Case Report presents staged endovascular exclusion of a rapidly enlarging mycotic RCIA aneurysm followed by recanalisation and stenting of a chronically occluded LCIV. Report A 57 year old man with disseminated methicillin resistant Staphylococcus aureus infection, lumbar spinal fusion hardware infection, and an inferior vena cava (IVC) filter placed for acute left lower limb deep vein thrombosis was found, during attempted filter retrieval, to have an uncannulatable left iliac venous system. Computed tomography angiography demonstrated a saccular RCIA aneurysm enlarging to approximately 4.5 cm over six months, compressing and occluding the LCIV with extensive pelvic collaterals. The aneurysm was excluded with overlapping covered stent grafts after internal iliac artery coil embolisation. One month later, the LCIV was recanalised and reconstructed with venoplasty and a dedicated venous stent, and the IVC filter was retrieved. The arterial endograft and venous stent remained patent throughout follow up; the excluded aneurysm progressively shrank and had completely resolved on imaging at approximately 31 months, with improved leg swelling. Conclusion A mycotic RCIA aneurysm is a rare cause of MTS. In a patient at high surgical risk with hardware infection, a staged endovascular approach—arterial aneurysm exclusion followed by interval venous reconstruction—achieved durable aneurysm exclusion, restored venous outflow, and permitted IVC filter retrieval, offering a minimally invasive alternative to open repair. The durability of implanting a vascular device within an infected field remains uncertain and mandates prolonged antimicrobial therapy and close surveillance.