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.

Most people do not know they have MTS, but it is identified when they are diagnosed 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 (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 ulcers.

Before choosing any treatment, it is important to discuss the potential benefits, risks, and side effects with your healthcare provider. You will receive specific guidelines to help you prepare for your procedure, as well as specific instructions to help your recovery.

The goals of treatment are to reduce symptoms and reduce the risk of complications. Your healthcare provider will recommend the treatment option that is right for you. The majority of treatments related to MTS are actually geared toward treating the DVT that is associated with the vein compression. The following are a number of different options that may be employed to treat patients presenting with DVT.

• Anticoagulation – Your physician may prescribe blood-thinning medication to prevent blood clots.
• Catheter-directed thrombolytic therapy – This is a nonsurgical treatment that uses clot-dissolving medications, referred to as thrombolytics, to dissolve blood clots. The medications can be delivered via a catheter, a long slender tube that is guided through the vein to the segment where the blood clot is located. The clot-dissolving drug is infused through the catheter into the clot. The clot usually dissolves in a matter of hours to a few days. In some cases, the narrowed area of the vein will need to be treated with angioplasty to prevent further clots from forming.
• Angioplasty and stenting – Angioplasty is a non-surgical treatment option used to widen the vein after a blood clot has been dissolved. During angioplasty, a small balloon at the tip of the catheter is inflated to stretch the vein open and increase blood flow. A stent is often placed during the angioplasty procedure to keep the vein open. A stent is a small, metal mesh tube that acts as a scaffold and provides support inside the vein. A balloon catheter, placed over a guide wire, is used to insert the stent into the narrowed vein. Once in place, the balloon is inflated and the stent expanded to the size of the vein holding it open. The balloon is deflated and removed, and the stent stays in place permanently. Stenting of the iliac vein is often important in the treatment of MTS. Once the blood clot is removed from the vein (typically by thrombolysis), the compressed vein is forced open with the use of a stent.

Outcomes of treatments for MTS are generally very good. Most patients, if identified shortly after the DVT has formed, can be adequately treated with complete resolution of their symptoms.