Definition

May-Thurner Syndrome

May-Thurner syndrome (MTS) happens when a blood vessel in the pelvis called the right common iliac artery presses on a nearby blood vessel called the left common iliac vein.

This can affect blood flow through your legs and can increase your chance of developing a blood clot (thrombosis). MTS has been associated with about 2-5% of all blood clots in the legs.

It is also called iliac vein compression syndrome.

MTS is a common finding on scans, affecting about 1 in 5 people.

Causes

May-Thurner Syndrome

MTS happens because the artery that carries blood to your right leg (right iliac artery) presses on the vein which carries blood from your left leg to your heart (left iliac vein). This can affect the flow of blood to your heart. Experts are not sure why this happens.

MTS is more common in women, those with scoliosis and those who have had radiation therapy.

It is not an inherited or genetic condition, so family members do not need to be screened.

Symptoms

May-Thurner Syndrome

MTS usually doesn’t cause any symptoms.

Some people may experience symptoms that include:

lower limb swelling
thigh or leg pain and tightness with exercise, which settles with rest and elevation (venous claudication)

Treatment

May-Thurner Syndrome

If you have MTS, you need to take measures to reduce your risk of developing a blood clot.

For example:

staying active
quitting smoking
making sure you stay hydrated.

For more information about preventing a blood clot, see thrombosis.

You should talk to your medical team if you have a condition that increases your risk of a blood clot (for example, if you are pregnant or if you have been diagnosed with cancer).

Find out about the symptoms of a blood clot in your leg (deep vein thrombosis or DVT). Being aware of the symptoms will help you know when to seek medical attention.

If a blood clot, it will usually be treated with anti-coagulation (blood thinners). Compression stockings are often helpful. Occasionally, you may need a treatment to break down the clot (thrombolysis). You may even need a stent to keep the vein open.