May-Thurner syndrome (Iliac vein compression syndrome)
May-Thurner syndrome denotes iliac vein compression by the crossing iliac artery at the iliocaval junction. Usually it is the left iliac vein which is compressed by the right iliac artery. The compression increases the risk of deep vein thrombosis. Other names for the syndrome are iliac vein compression syndrome and Cockett syndrome. The obstruction may cause varicosities in the affected limb and ulcers due to chronic venous stasis. The pulsations of the overlying artery causes intimal hypertrophy of the vein which adds to the severity of the obstruction. Some reports show that deep vein thrombosis occurs three to eight times more commonly on the left side. The original report was: MAY R, THURNER J. The cause of the predominantly sinistral occurrence of thrombosis of the pelvic veins. Angiology. 1957;8:419-27. Since May-Thurner syndrome is a progressive disease, surgical options like vein patch angioplasty and repositioning of the iliac artery have been tried in the past. Implantation of a self expanding stent is another option. May-Thurner syndrome should be thought of in the differential diagnosis of edema of the left leg and the diagnosis can be confirmed by venography.