Blood Disorders Basics of May-Thurner Syndrome By Amber Yates, MD Amber Yates, MD LinkedIn Twitter Amber Yates, MD, is a board-certified pediatric hematologist and a practicing physician at Baylor College of Medicine. Learn about our editorial process Updated on January 17, 2022 Medically reviewed Verywell Health articles are reviewed by board-certified physicians and healthcare professionals. These medical reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Scott Sundick, MD Medically reviewed by Scott Sundick, MD LinkedIn Scott Sundick, MD, is a board-certified vascular and endovascular surgeon. He currently practices in Westfield, New Jersey. Learn about our Medical Expert Board Fact checked Verywell Health content is rigorously reviewed by a team of qualified and experienced fact checkers. Fact checkers review articles for factual accuracy, relevance, and timeliness. We rely on the most current and reputable sources, which are cited in the text and listed at the bottom of each article. Content is fact checked after it has been edited and before publication. Learn more. by Nick Blackmer Fact checked by Nick Blackmer LinkedIn Nick Blackmer is a librarian, fact-checker, and researcher with more than 20 years’ experience in consumer-oriented health and wellness content. Learn about our editorial process Print May-Thurner syndrome—also called iliac vein compression—occurs when the right iliac artery crosses over the left iliac vein. Occasionally, this can lead to compression of the iliac vein at that location. This change in anatomy increases the chance of developing a deep vein thrombosis (DVT). Tetra Images / Getty Images Symptoms of May-Thurner Syndrome Symptoms of May-Thurner syndrome can include pain and/or swelling, though in many cases there are no symptoms. Symptomatic May-Thurner syndrome occurs more commonly in women in their 20s and 30s. Often it is diagnosed during the treatment of DVT. Increased Risk of Blood Clots Compression of the left common iliac vein causes irritation/injury to the blood vessel, resulting in the thickening of the blood vessel wall. This thickening of the blood vessel wall causes pooling of the blood (also called stasis), which increases the risk of clot formation. This risk factor, combined with other risk factors for clot formation, such as hormonal contraception (birth control pills) or prolonged inability to walk after surgery, may further increase this risk. Diagnosis May-Thurner syndrome is typically diagnosed with imaging tests such as color Doppler ultrasound, computed tomography angiography, or magnetic resonance venography (MRI of the veins). Intravascular ultrasound (ultrasound within the blood vessel) can be very helpful in visualizing the compression of the left common iliac vein. Diagnosis of May-Thurner syndrome is often followed by a workup (sometimes called a “hypercoagulable workup”) looking for other risk factors for clot formation. Treatment Options If a blood clot is present, treatment with anticoagulation is required. Unfortunately, long-term treatment with anticoagulation (blood thinners like heparin, enoxaparin, or warfarin) is not sufficient, because the clot must be removed to prevent the development of post-thrombotic syndrome. Treatment with “clot-buster” medication like tissue plasminogen activator (tPA) is often required at the time of diagnosis; tPA is usually delivered via a catheter directly to the area of the clot. Treating the blood clot is only one part of the treatment. Removing the blood clot will not treat the underlying problem of the left common iliac vein being compressed, putting it at high risk of clot formation. To prevent further blood clot formation, a stent—a small wire mesh—may be placed to keep the vein open. These treatments (tPA and stent placement) may occur at the same time as intravascular ultrasound, allowing confirmation of the diagnosis and definitive treatment. Anticoagulation treatment will be generally be continued for a few months after stent placement, but it may not be required long term. 6 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Radaideh Q, Patel NM, Shammas NW. Iliac vein compression: epidemiology, diagnosis and treatment. Vasc Health Risk Manag. 2019;15:115-122. doi:10.2147/VHRM.S203349 Liddell RP, Evans NS. May-Thurner syndrome. Vasc Med. 2018;23(5):493-496. doi:10.1177/1358863X18794276 Knuttinen MG, Naidu S, Oklu R, et al. May-Thurner: diagnosis and endovascular management. Cardiovasc Diagn Ther. 2017;7(S3):S159-S164. doi:10.21037/cdt.2017.10.14 American Heart Association. Understand your risk for excessive blood clotting. Reddy D, Mikhael MM, Shapiro GS, Farrell T. Extensive deep venous thrombosis resulting from anterior lumbar spine surgery in a patient with iliac vein compression syndrome: a case report and literature review. Global Spine J. 2015;5(4):22-27. doi:10.1055/s-0034-1396431 Meissner MH, Gloviczki P, Comerota AJ, et al. Early thrombus removal strategies for acute deep venous thrombosis: clinical practice guidelines of the Society for Vascular Surgery and the American Venous Forum. J Vasc Surg. 2012;55(5):1449-1462. doi:10.1016/j.jvs.2011.12.081 By Amber Yates, MD Amber Yates, MD, is a board-certified pediatric hematologist and a practicing physician at Baylor College of Medicine. See Our Editorial Process Meet Our Medical Expert Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? 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