What is May-Thurner Syndrome (MTS), also known as Iliac Vein Compression Syndrome?

May-Thurner syndrome (MTS) is caused when the left iliac vein is compressed by the right iliac artery, which increases the risk of deep vein thrombosis (DVT) in the left extremity. DVT is a blood clot that may partially or completely block blood flow through the vein.

When should I seek treatment for May-Thurner Syndrome?

Most people do not know they have MTS, but it is identified when they present with a DVT.
Patients should seek treatment for symptoms, including swelling, pain or tenderness in the leg, feeling of increased warmth in the leg, redness or discoloration of the skin, or enlargement of the veins in the leg.

Even though DVT itself is not life-threatening, the blood clot has the potential to break free and travel through the bloodstream, where it can become lodged in the blood vessels of the lung (known as a pulmonary embolism). This can be a life-threatening condition.

DVT can also lead to complications in the legs referred to as chronic venous insufficiency link (also known as post-thrombotic syndrome). This condition is characterized by pooling of blood, chronic leg swelling, increased pressure, increased pigmentation or discoloration of the skin, and leg ulcers known as venous stasis ulcer.

Reviewed: 12/15

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy