Iliac vein compression syndrome (also called May-Thurner Syndrome) occurs when the left iliac vein is externally compressed by the right common iliac artery. This condition increases the chances of extensive symptomatic DVT involving the entire leg. Prolonged untreated conditions can lead to chronic venous insufficiency, due to extensive trauma from the large amount of clot retained in the veins. This condition is more common in middle-aged women, but can also be seen in men.
Presentation of iliac vein compression presents as leg swelling and pain from the thigh extending to the feet, and typically involves the left leg, but sometimes may involve the right leg in rarer cases. Patients may also develop increased warmth in the leg, skin discoloration, and vein engorgement.
After discovery of a DVT, venous ultrasound often will identify if the clot extends in the iliofemoral region of the leg. CT venography will often demonstrate dilated veins in the pelvis full of thrombus, just distal to the adjacent iliac artery. If May-Thurner syndrome is suspected, intravascular ultrasound is used to pinpoint the exact area where the artery is compressing the vein, and clot will be seen below that narrowing.
Treatment of this condition involves multiple modalities, which include IVC filter placement to prevent migration of clot to the lungs, followed by delivering powerful drugs locally to soften and dissolve the clot, followed by removing the clot using catheters. Finally, balloon angioplasty is used to stretch the vein to improve venous return and a stent is placed to prevent the artery from re-closing the vein, thereby preventing future leg clots.