What is May-Thurner Syndrome

May-Thurner Syndrome (MTS), also known as Iliac Vein Compression Syndrome, is a relatively rare yet potentially severe condition affecting the veins in the pelvis. It occurs when the left iliac vein becomes squeezed or compressed by the neighboring right iliac artery, potentially leading to back-pressure in the leg.

The syndrome was first identified in 1851 by Drs. May and Thurner, hence its name. It is not a particularly common disease and is believed to be under-diagnosed and under-treated in the medical community.

May Thurner Syndrome

Illustration of May-Thurner Syndrome

Causes of May-Thurner Syndrome

In human anatomy, the major pelvic veins known as iliac veins serve as crucial pathways for blood returning from the legs to the heart. These veins naturally lie between the spine and arteries, with some level of compression being typical.

However, when this compression becomes exaggerated, it can cause May-Thurner syndrome. While the left leg is most commonly affected, the condition can also impact both legs.

Symptoms of May-Thurner Syndrome

Symptoms of May-Thurner vary, ranging from mild discomfort to complications such as severe blood clots. Many patients experience one-sided leg pain and swelling, often misdiagnosed for years. Over time, chronic back pressure from MTS may cause varicose veins, chronic venous insufficiency, skin pigmentations, and ulcers. In severe cases, the compression can restrict blood flow, resulting in blood clots known as iliofemoral deep vein thrombosis (DVT).

MTS is frequently seen when we are treating acute illnesses or trauma. The additional stress on the body can cause the blood to thicken which decreases the blood flow through the compressed iliac vein. MTS is more prevalent in women and commonly occurs in individuals aged 20 to 50.

Diagnosing May-Thurner Syndrome

MTS can be diagnosed through various methods. Initial assessments typically involve venous ultrasound of the legs to assess downstream effects. The ultrasound does not usually image the iliac vein directly, it can direct the physician to look at other causes.

Imaging studies such as CT or MRI scans of the abdomen and pelvis are a good way to see the iliac veins and detect MTS. Formal venography with intravascular ultrasound is considered the gold standard diagnostic test for MTS.

Treatment of May-Thurner Syndrome

The vascular surgeons at Fox Valley Surgical Specialists have a variety of treatments for MTS. Compression stockings are often recommended initially to alleviate swelling non-surgically.

Procedural steps that most physicians will follow to relieve iliac vein compression are:

MTS with Left Iliac Stents

The images here show a patient in her 80s. Her symptoms included leg swelling as well as skin ulcers that were non-healing. A diagnostic venogram confirmed iliac vein compression.

Several stents were placed resulting in drastically improved leg swelling and healing of her skin ulcers.

MTS with Bilateral Iliac Stents

This female patient in her 20s experienced extensive left leg swelling and blood clots which were significantly limiting her quality of life. The diagnostic venogram showed occlusions of both iliac systems as well as associated veins.

After declotting both veins and placing stents in the inferior vena cava (IVC) in a kissing fashion, the patient had a drastic reduction of leg swelling and is back to leading a normal life.

MTS with Left Iliac Stents

Your Experienced Vascular Team

Dr. Robert Ballard

Robert Ballard, MD

Dr. Alexander Tretinyak
Alexander Tretinyak, MD
Sarah Wilson, MD
Sarah Wilson, MD
Dr. Jason Le
Jason Le, MD
Ariel Stilp
Ariel Stilp, APNP