May-Thurner Syndrome

May-Thurner syndrome is the result of the compression of the left iliac vein.The right iliac artery, which normally lays over the iliac vein, is the cause of this condition. In this syndrome, the right iliac artery constricts the iliac vein which narrows as a result of the constriction and sometimes scars. An individual with May-Thurner syndrome is at increased risk for developing deep vein thrombosis, or DVT, a potentially serious blood clot that can completely obstruct the circulation of blood in that vein. Such an individual may also develop venous insufficiency as a result of the deep vein thrombosis, known as post-thrombotic syndrome.

May-Thurner syndrome is a thrombotic disorder, a condition that interferes with the normal flow of blood. The anatomical variant responsible for the syndrome is congenital but not hereditary, more common in women than men. The syndrome shows up more frequently in young women taking birth control medication and as women age or gain weight. While a high percentage of the population has some degree of compression of the iliac vein, only a small number of individuals have severe compression resulting in symptoms.

Symptoms of May-Thurner Syndrome

Since May-Thurner syndrome must be diagnosed through testing, most patients are unaware that they have the condition, even when the iliac vein is extremely compressed unless they develop a deep vein thrombosis. While DVT alone is not life-threatening, there is a significant danger that the blood clot may break loose and travel through the body, resulting in the danger of a potentially fatal pulmonary embolism.

Symptoms of deep vein thrombosis may include any or all of the following conditions in the affected leg:

  • Swelling, pain or tenderness
  • Increased warmth
  • Redness or discoloration of the skin
  • Enlargement of the veins
  • Ulcerations

Diagnosis of May-Thurner Syndrome

The majority of patients are not diagnosed with May-Thurner syndrome until they develop DVT. Diagnosis may include the following:

  • Physical examination
  • Complete family history
  • Ultrasound, CT scan or MRI scan
  • Venography with contrast dye
  • Intravascular ultrasound

Treatment of May-Thurner Syndrome

There are several treatments for May-Thurner syndrome. All are focused on reducing symptoms and the risk of complications. Treatment options for May-Thurner syndrome may include:


Anticoagulants are medications to thin the blood. If blood thinners are prescribed, the patient must be carefully monitored since there is a danger of excessive bleeding.

Catheter-Directed Thrombolytic Therapy

Catheter-directed thrombolytic treatment involves inserting a catheter into a vein in the leg and threading it through the circulatory system to the site of the blood clot. At the location of the clot, the catheter dispenses a thrombolytic drug. This procedure is performed using X-rays and ultrasound scans to ensure precision.

Angioplasty and Stenting

After a blood clot has been successfully dissolved, angioplasty is sometimes performed to widen the blood vessel. When the clot has been removed, the compressed iliac vein is opened with the use of a stent.

Vena Cava Filters

Vena cava filters are a viable treatment option for patients unable to take anticoagulant medications. Vena cava filters are inserted in the vena cava, the largest vein in the body, during a surgical procedure. Once the filter is inserted, it can trap clots as they travel through the body, before they reach the lungs.

The prognosis for patients with May-Thurner syndrome is usually good, particularly if the syndrome is diagnosed and treated in its early stages.

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