May-Thurner Syndrome
Also called iliac vein compression syndrome, or Cockett syndrome
A vascular condition in which the right common iliac artery presses down on the left common iliac vein ā the main vein draining the left leg ā pinning it against the fifth lumbar vertebra behind it. The trapped vein narrows and can scar over time, obstructing the return of blood from the leg. The result is venous congestion ā swelling, heaviness, and aching ā and a strong predisposition to deep vein thrombosis (DVT) on the left side.
The Anatomy ā in Plain Terms
An artery lies across the main vein draining your left leg and presses it shut ā like a foot resting on a garden hose. Blood flows down into the leg just fine; it's the return trip that's blocked. So it backs up ā a slow traffic jam building in the vein ā and where blood pools and stalls, it clots.
Because the artery pulses against the vein with every heartbeat, the vein wall can thicken and form internal scar-like webs ("spurs"), narrowing the channel further. This is why the compression tends to worsen, not resolve, on its own ā and why the body often grows small detour veins (collaterals) to route blood around the blockage.
Source
Definition adapted from Harbin MM, Lutsey PL, et al., "May-Thurner Syndrome," StatPearls (NCBI Bookshelf, National Library of Medicine) ā a peer-reviewed clinical reference.
Key Points
- The classic anatomy is the right common iliac artery compressing the left common iliac vein ā which is why the left leg is affected far more often than the right.
- It can be silent for years (nonthrombotic), or first announce itself as a sudden left iliofemoral DVT (thrombotic). Guidelines say to suspect it in anyone with an unexplained left-leg iliofemoral clot.
- Classically described in women in their 20sā40s, but it occurs in men ā the case documented on this site is a male patient.
- Diagnosed by ultrasound, CT or MR venography, and catheter venography with intravascular ultrasound (IVUS) ā the reference standard for measuring the compression.
- Treated by opening the compressed segment with a balloon (angioplasty) and holding it open with a venous stent, usually with blood thinners; an acute clot may also need clot-dissolving therapy. Restoring outflow relieves both the congestion and the clotting risk.
On AbilityForge
May-Thurner syndrome is where Michael Kissling's case begins. Three specialists independently confirmed it ā a hematologist and a vascular surgeon on exam, and an MR venogram that showed the left iliac vein narrowed "to an appearance of occlusion" exactly where it passes between the right common iliac artery and the L5 vertebra, with the body already sprouting collateral veins around the blockage.
The indicated fix was a venous stent ā placed before the backed-up blood turned into wounds, when the odds of success were highest. That stent was denied. The condition was left to progress until the non-healing wounds the stent existed to prevent became the very criteria the insurer later demanded. This page is the anatomy sitting at the root of everything downstream.
See Also