Why Many People Don’t Need a Stent for May–Thurner Syndrome

If you’ve ever had a CT scan, MRI, or ultrasound of your abdomen or pelvis, you may have been told you have something called May–Thurner syndrome or “iliac vein compression.”

Here’s the key point: mild pressing of the left iliac vein is a common, normal anatomic finding, and most people who have it are healthy, have no symptoms, and do not need a stent.

You can read more about deep vein thrombosis basics in our condition guide.

Let’s break it down.

What Is May–Thurner Syndrome?

May–Thurner syndrome happens when the right common iliac artery crosses over and presses on the left common iliac vein in the pelvis, pinching it against the spine. Veins carry blood out of the leg and back toward the heart. When the vein is squeezed hard enough over time, it can become scarred and narrowed, which slows blood from draining out of the left leg. This is a problem with blood leaving the leg (a vein problem), not with blood flowing into the leg (the arteries are not blocked).

Important distinction:

• “Iliac vein compression” (the artery gently resting on the vein) is a normal anatomic variant seen in a large share of healthy people. By itself it causes no symptoms.
• “May–Thurner syndrome” is the term used only when that compression actually causes problems — significant narrowing, symptoms, or a blood clot.

When it does cause problems, symptoms can include:

• Significant left leg swelling
• Leg heaviness, aching, or cramping that is worse with activity and better with elevation
• A deep vein thrombosis (DVT) — a blood clot in the deep veins of the leg or pelvis

Most people told they have “iliac vein compression” on a scan have the harmless anatomic version, not the syndrome.

So Why Are Stents Sometimes Recommended?

Imaging tests (CT, MRI, ultrasound, or a specialized test called IVUS) can show a vein that looks narrow. But a narrow-looking vein on a picture does not, by itself, prove the vein is causing symptoms. Many normal veins look narrowed on a scan yet work perfectly well. In recent years, some people have been told that this normal narrowing is:

• “Dangerous”
• “Blocking blood flow”
• “Causing their leg symptoms”
• A reason to place a stent

In fact, none of that may be true. Medical guidelines are clear that stents should not be placed for compression found incidentally on imaging in someone without matching symptoms.

Stents Are Helpful for the Right Patients — But Are Not Risk-Free

For carefully selected patients with true symptoms or a clot, stenting is generally safe and often works very well. But a vein stent is permanent and cannot easily be removed once placed, so it should only be used when truly needed. Possible downsides include:

• Re-narrowing or clotting inside the stent over time
• Rarely, the stent moving (migrating) or fracturing
• The possible need for blood thinners and long-term follow-up imaging
• Additional procedures if a problem develops

Because of this, guidelines recommend trying conservative (non-surgical) treatment first and reserving stents for people with clear, significant symptoms or a true blockage.

What Actually Suggests True May–Thurner Syndrome?

A stent is most likely to help when someone has:

• A deep vein thrombosis (DVT) in the pelvic/leg veins linked to the compression
• Significant, ongoing left leg swelling
• Leg heaviness or cramping with activity (sometimes called venous claudication) that clearly points to a blocked vein
• Skin changes or a venous leg ulcer from long-standing venous problems

Mild swelling, general leg tiredness, varicose veins, or pelvic discomfort are usually caused by other, more common problems — not by iliac vein compression.

What Should Patients Do?

If you’ve been told you have May–Thurner syndrome or iliac vein compression, here’s what to keep in mind:

1. A second opinion is reasonable, especially if a stent is recommended right away based mainly on a scan.
2. Ask whether your symptoms truly match a blocked vein. Often they don’t.
3. Make sure a full leg vein ultrasound has been done. Many leg symptoms come from vein problems lower in the leg, not from the pelvis.
4. Conservative treatment often helps and is usually tried first: compression stockings, leg elevation, exercise and weight management, and treating any surface (varicose) vein problems.
5. Stents should generally be a considered step for the right patient — not an automatic first move based on imaging alone.

The Bottom Line

A compressed iliac vein on a scan is very common and often completely normal. Most people with this finding do not have May–Thurner syndrome and do not need a stent. Stents genuinely help the smaller group of people with real symptoms or a clot.

If you’ve been told you need a stent, it’s okay to pause, ask questions, and get another opinion.