May-Thurner Syndrome: What to Know About This Underrecognized Condition

Most people have never heard of May-Thurner Syndrome (MTS) — and surprisingly, many physicians haven’t either. In nearly 30 years of training and practice, the condition received very little attention in medical school, residency, CME courses, or even vascular rotations.

For years, when a patient came to me with swelling, aching, heaviness, or discoloration in one leg — usually the left — I diagnosed “chronic venous insufficiency” and recommended elevation and compression stockings. And like many patients will tell you, those steps often did little to help.

That changed when I met Scott Hollander, DO, an interventional radiologist, who introduced me to MTS. What I learned significantly shifted how I evaluate left-leg swelling, pain, and unexplained blood clots in my practice.

What Is May-Thurner Syndrome?

MTS occurs when a major pelvic artery compresses a significant pelvic vein. The right iliac artery sits on top of the left iliac vein — an overlap we all share — but in some people, the constant pressure slowly narrows the vein.

Over time, the vein becomes narrowed, irritated, and less able to move blood the way it should; this can cause:

• swelling in one leg (usually the left)
• pain or aching
• heaviness or fatigue
• skin discoloration
• blood clots called deep vein thrombosis (DVT)

The tricky part is that the symptoms often look like many other common issues — aging, varicose veins, pregnancy, long hours standing or sitting — which leads to frequent misdiagnosis. Even common tests like standard leg ultrasounds often miss it, because the compression occurs higher up in the pelvis, where a Doppler ultrasound can’t easily visualize the vein.

Why Is MTS So Often Overlooked?

For decades, medical training focused heavily on arterial disease — heart attacks, strokes, aneurysms — while venous disease received far less attention. As a result, many clinicians did not routinely learn to consider iliac vein compression when evaluating leg symptoms.

Diagnosing MTS also requires specific technology. The most accurate test is intravascular ultrasound (IVUS), a procedure performed by endovascular specialists. Without IVUS, clinicians may not detect MTS.

The Good News: Treatment Exists and Works

For patients who develop a blood clot, treatment may include blood thinners or, in severe cases, a minimally invasive procedure to break up the clot.

But for patients whose symptoms come from long-term vein compression rather than an active clot, the most effective treatment is placing a small, flexible stent inside the vein to hold it open.

These treatments are well-established. The FDA has cleared several stents for venous use, functioning within the low-pressure venous system. Many patients report reductions in swelling, discomfort, and limitations in daily activities after treatment. Insurance plans, including Medicare, commonly provide coverage.

Raising Awareness

MTS is not rare; it is often underdiagnosed. Research suggests that up to 20–25% of people may have some degree of left iliac vein compression, yet only a small number undergo evaluation. My own wife was one of them.

More specialists today have the expertise to identify and treat this condition using IVUS, high-quality imaging, and FDA-approved venous stents. As a result, many patients can finally get answers and relief.

A Commitment to Our Patients

At SeretisCare Family Practice, we identify patients who may require further evaluation and partner with specialists who have expertise in treating this condition.

If you or someone you know has persistent left-leg swelling, heaviness, aching, discoloration, or a history of a left-sided DVT, May-Thurner Syndrome may be part of the explanation — and we have the tools to treat it.