May-Thurner syndrome is the narrowing of the vein that runs from the left leg (left common iliac vein) to the large vein in the abdomen that goes to the heart. May-Thurner syndrome can lead to leg pain and swelling or even deep vein thrombosis (a blood clot that develops in the large veins of the legs and pelvis).
May-Thurner syndrome is caused when the artery that runs to the right leg (right common iliac artery) compresses the left iliac vein against the spine and causes it to become narrowed and scarred. While the right common iliac artery normally runs over the left common iliac vein, it does not usually cause pressure and narrowing of the vein.
There are no known risk factors for May-Thurner syndrome, though it is more common in women.
Patients with May-Thurner syndrome may not have any symptoms even with a moderate amount of vein narrowing. However, symptoms can occur with more severe cases and include:
- Leg swelling and pain
- Blood clots
- Deep vein thrombosis
- Ultrasound Imaging: Sound waves are used to create an image of the veins and identify the presence of blood clots.
- Magnetic Resonance Imaging (MRI) or Computed Tomography (CT) scans: Images are made that can show if the vein is being compressed or if there is a blood clot present in the vein.
- Venogram or phlebogram: This procedure injects a dye into a foot vein to make blood flow visible on an X-ray, which measures blood flow in the veins and look for signs of clots or compression of the vein by the artery.
Surgical options for treating May-Thurner syndrome include:
- Stenting: A stent works like a scaffold to help to hold the vein open and relieve the blockage in the vein. This treatment is done through a small incision without the need for open surgery. This is called a minimally invasive procedure.
- Bypass surgery: Blood flow is rerouted around the narrowed portion of the vein using a bypass graft.
- Repositioning the right common iliac artery: The artery is surgically moved behind the left common iliac vein so that the artery no longer puts pressure on the vein.
- Building a tissue "sling": Tissue is surgically placed between the left common iliac vein and the right common iliac artery, lifting the artery so it no longer places pressure on the vein.
- Removal of blood clot: If the vein in the pelvis is full of blood clots and the leg is swollen, the blood clot can be removed using blood-clot dissolving medicine, in combination with a device that helps to break up and remove the clot. This procedure is done without performing open surgery. If a blood clot is present, then surgery or placement of a stent is not performed until the clot has been removed.