May - Thurner syndrome: a case report of a lethal undiagnosed left iliac vein thrombosis

May-Thurner syndrome (MTS), also known as iliac vein compression syndrome, is a pro-thrombotic condition caused by the compression of the left iliac vein by the right common iliac artery, often resulting in deep vein thrombosis (DVT). MTS accounts for 2-5% of all DVT cases and is often underdiagnosed due to the difficulty of assessing the deep pelvic veins. We present the case of a 63-year-old female with a history of Crohn's disease and scoliosis, who developed lower limb pain and venous ulcers. Despite negative Doppler ultrasound and exclusion of other conditions such as diabetes and vasculitis, the patient deteriorated after a fall, leading to cardiogenic shock and death. Autopsy revealed a thrombus in the left iliac vein and an embolus in the inferior vena cava, causing fatal venous obstruction. Histological examination confirmed thrombotic formations in both sites and assigned the iliac thrombus to phase III of thrombus organization, indicating that it predated the terminal event by several days. This case underscores the importance of comprehensive evaluation in patients with lower limb ulcers and pain, as Doppler ultrasound alone may not detect deeper venous abnormalities such as MTS. Advanced imaging techniques, including multi-detector computed tomography venography or magnetic resonance venography, may be necessary to diagnose MTS in such cases, preventing life-threatening complications.