May-Thurner syndrome is a vascular condition in which the right iliac artery presses against the left iliac vein, narrowing it against the spine. This compression can slow blood flow out of the left leg and raise the risk of deep vein thrombosis (DVT). Understanding what is May-Thurner syndrome helps patients recognize symptoms early and discuss appropriate evaluation with a vascular specialist.
What Causes May-Thurner Syndrome?
May-Thurner syndrome results from an anatomical relationship in the pelvis. The right common iliac artery crosses over the left common iliac vein, and over time, the repeated pulsing of the artery can compress the vein against the lumbar spine.
Some degree of this crossing anatomy is common in the general population, but only some individuals develop symptomatic compression severe enough to cause clinical problems. Contributing factors may include:
- Anatomical variation in vessel positioning
- Formation of scar tissue (spurring) inside the vein from chronic compression
- Pregnancy, which can increase pelvic venous pressure
- Prolonged immobility or dehydration
What Are the Symptoms of Iliac Vein Compression?
Symptoms often appear in the left leg, since that is the side typically affected. Common signs include:
- Swelling of the left leg or ankle
- Aching, heaviness, or fatigue in the leg, especially after standing
- Visible varicose veins in the leg or pelvic region
- In more advanced cases, skin discoloration or discomfort consistent with chronic venous insufficiency
Some people with May-Thurner anatomy have no symptoms at all and are only diagnosed after an unrelated imaging study or after developing a DVT. If you notice new or worsening leg swelling, it is important to consult a qualified healthcare professional promptly, as this can also indicate a blood clot requiring urgent evaluation.
How Is May-Thurner Syndrome Diagnosed?
Physicians typically use imaging to confirm iliac vein compression, which may include:
- Duplex ultrasound of the leg veins
- CT venography or MR venography to visualize the pelvic veins
- Intravascular ultrasound (IVUS) during a catheter-based procedure, which can show compression that other imaging may miss
How Is May-Thurner Syndrome Treated?
Treatment approaches depend on symptom severity and whether a blood clot is present. Options a physician may consider include:
- Anticoagulation, if an associated DVT is present, to reduce clot progression
- Catheter-based clot removal, when an acute thrombus is contributing to the obstruction
- Venous stenting, using a dedicated venous stent designed to hold the compressed vein open and restore blood flow
Dedicated venous stents, such as the INVAMED Atlas Venous Stent, are self-expanding nitinol devices engineered specifically for venous anatomy. Unlike arterial stents, they are designed with greater flexibility and crush resistance to withstand the external compression seen in May-Thurner syndrome. A physician determines candidacy for stenting based on imaging findings, symptom severity, and overall health.
Frequently Asked Questions
Is May-Thurner syndrome the same as DVT?
No. May-Thurner syndrome is an anatomical compression of the iliac vein, while DVT is a blood clot. However, the compression associated with May-Thurner syndrome can increase the likelihood of developing a DVT in the affected leg, so the two conditions are often connected.
Can May-Thurner syndrome go undiagnosed for years?
Yes. Many people have the underlying anatomical compression without symptoms for years, and it may only be identified after a DVT episode or during imaging performed for another reason.
Who typically evaluates a patient for venous stenting?
Vascular surgeons, interventional radiologists, or interventional cardiologists typically evaluate candidacy for venous stenting based on imaging studies, symptom pattern, and clot history. Suitability for any procedure is determined on an individual basis by the treating physician.
Related INVAMED Resources
- Venous Stents — dedicated stent systems for iliofemoral venous outflow obstruction
- Deep Vein Thrombosis (DVT) — devices for DVT-related venous interventions
- Contact INVAMED — request information about venous stent systems
Medical Disclaimer: This article is provided for general informational and educational purposes only and does not constitute medical advice, diagnosis, or treatment recommendation. It is not a substitute for consultation with a qualified healthcare professional. Product indications, availability, and regulatory status vary by country. Always refer to the official Instructions for Use (IFU) and consult a licensed physician for guidance specific to your situation. INVAMED devices are intended for use by trained healthcare professionals.