A minimally invasive stent treats the compressed left iliac vein at the root of unexplained leg swelling or DVT — replacing older surgical bypass approaches.
May-Thurner syndrome (MTS) is a vascular condition in which the left common iliac vein — which carries blood from the left leg and pelvis back toward the heart — gets pinched between the right common iliac artery running across it and the bony spine behind it. Over time, this repeated compression can scar and narrow the vein, slowing blood flow out of the left leg and raising the pressure within it.
This anatomical arrangement is actually fairly common and often causes no problems at all — some degree of compression is present in a large proportion of people without ever producing symptoms. MTS becomes a clinical diagnosis, not just an anatomical one, when this narrowing is severe enough, or has gone on long enough, to actually cause symptoms or a blood clot.
Swelling, heaviness, or aching in the left leg, often worse by the end of the day, without a clear explanation on routine ultrasound.
Sudden left leg swelling and pain from a clot forming in the narrowed vein — often the first sign of the underlying compression.
Chronic swelling, skin changes, and sometimes ulceration developing after a previous, incompletely treated DVT.
A needle puncture is made behind the knee or in the groin under ultrasound guidance.
Contrast dye and intravascular ultrasound map the compressed segment precisely.
A self-expanding venous stent holds the compressed segment open long-term.
Most patients go home the same day or after a short overnight stay.
MTS is classically described in women in their 20s to 40s, though it can affect anyone and is frequently under-recognised, in part because it can be mistaken for more common causes of leg swelling. It presents along a spectrum:
Chronic venous symptoms without a clot — swelling, heaviness, aching, or visible varicose veins in the left leg, often worse by the end of the day, that don't fully explain themselves on a routine leg vein ultrasound.
Acute deep vein thrombosis — sudden left leg swelling and pain caused by a clot forming in the narrowed, slow-flowing vein — often the first sign that brings the underlying compression to light, especially in a younger patient without other typical DVT risk factors.
Post-thrombotic syndrome — in patients who had a previous DVT that wasn't fully treated or whose underlying compression was never identified, chronic swelling, skin changes, and sometimes ulceration can develop over the following months to years.
Because a standard leg vein Doppler ultrasound focuses on the veins of the leg itself, it can miss the compression happening higher up, in the pelvis, unless the sonographer or referring clinician specifically thinks to look there. Persistent one-sided leg swelling that doesn't fully fit the usual picture, or a DVT occurring without an obvious trigger — especially in a younger patient — should prompt a closer look for MTS as the underlying cause.
Cross-sectional imaging — a CT or MR venogram of the pelvis — is usually the first step, showing the artery compressing the vein and giving a good overall picture of the anatomy. Where treatment is being considered, intravascular ultrasound (IVUS), performed from inside the vein at the time of the procedure, is the most sensitive way to confirm the degree of compression and plan exactly where a stent needs to sit — it can reveal narrowing that even good cross-sectional imaging underestimates.
May-Thurner syndrome should be treated only when it's symptomatic — incidental compression found on a scan for another reason doesn't automatically need intervention. Where treatment is indicated, endovascular therapy has replaced older surgical bypass approaches as the standard of care, since it addresses the underlying mechanical compression directly rather than just managing its consequences.
Access: a needle puncture is made into a vein, usually behind the knee (popliteal) or in the groin, under ultrasound guidance.
Venogram and IVUS: contrast dye and intravascular ultrasound map the compressed segment precisely.
Balloon venoplasty: a balloon catheter is used to gently expand the narrowed vein.
Stenting: a self-expanding metal mesh stent, sized specifically for the venous system, is placed across the compressed segment to hold it open long-term.
If an acute clot is present, catheter-directed thrombolysis or mechanical thrombectomy is used first to clear it, with stenting of the underlying compression typically done in the same or a closely following session, since treating the clot alone without addressing the compression underneath it leaves the person prone to the clot recurring.
The whole procedure is done through the single puncture site, without any open incision, and most patients go home the same day or after a short overnight stay.
Patients are generally placed on a period of anticoagulation (blood-thinning medication) after stenting to keep the new stent open while the vein lining heals around it, with the exact duration individualised to whether the patient had an acute clot or compression alone. Because these patients are often young with an otherwise long life ahead of them, maintaining long-term stent patency really matters, and most patients see substantial, often dramatic, improvement in leg swelling and discomfort once flow through the vein is restored.
Getting May-Thurner syndrome right — recognising it as the cause of an otherwise unexplained leg problem, confirming it precisely with IVUS, and placing a correctly-sized venous stent across exactly the right segment — depends on specific experience with venous, rather than purely arterial, intervention. Getting the diagnosis and the stent placement right the first time matters, since these patients are often young, and a well-placed stent can offer years of relief from a problem that's frequently been misattributed to other causes for a long time before the real diagnosis is made.
The right common iliac artery crosses over and compresses the left common iliac vein against the spine. This anatomical arrangement is common, but in some people it narrows the vein enough to cause symptoms or trigger a blood clot.
Because of the anatomy — it's specifically the left common iliac vein that runs beneath the right common iliac artery at this crossing point, which is why symptoms are almost always one-sided, on the left.
No — it should be treated only when it's causing symptoms. Incidental compression seen on a scan done for another reason doesn't by itself require intervention.
No — it's a minimally invasive, catheter-based procedure done through a single needle puncture, usually behind the knee or in the groin, with no open surgical incision.
Yes, typically for a period after the procedure, to protect the stent while the vein heals around it. The exact duration depends on whether you had an acute clot alongside the compression.
Book a consultation with Dr. Giragani, or send your scans for a specialist second opinion.