May-Thurner syndrome (MTS), also called iliac vein compression syndrome or May-Thurner disease, is a vascular condition that can increase the risk of , particularly in the left leg. MTS is often underdiagnosed because some people have mild or no symptoms until swelling, discomfort, or a blood clot develops.
Once diagnosed, May-Thurner syndrome can be managed effectively. Early evaluation helps confirm what’s causing these symptoms and determine treatment.
What Is May-Thurner Syndrome?
May-Thurner syndrome occurs when the right iliac artery compresses the left iliac vein in the pelvis, slowing blood flow from the left leg back toward the heart.
Typically, arteries carry blood away from your heart, and veins bring blood back to your heart. In May-Thurner syndrome, the right iliac artery presses against the left iliac vein, and over time, this pressure can partially block the vein.
The disruption of blood flow may cause:
- Swelling in the left leg
- A feeling of heaviness or aching
- Increased risk of deep vein thrombosis (DVT)
If you notice unexplained swelling in one leg, particularly the left, visit a vein specialist for a consultation.
May-Thurner Syndrome Symptoms
One of the challenges with May-Thurner syndrome is that many people have no warning signs, so they do not realize they have it until they develop a blood clot.
When May-Thurner syndrome symptoms are present, they may include:
- Swelling in the left leg
- One leg appears more swollen than the other
- Leg pain, aching, or heaviness
- Tightness or discomfort that worsens with prolonged standing
- Skin discoloration or other skin changes
- Venous ulcers in more advanced cases
If unexplained swelling or persistent discomfort develops in one leg, a vein specialist can help determine whether May-Thurner syndrome or another venous condition may be contributing.
When Symptoms Need Immediate Medical Attention
May-Thurner syndrome can cause deep vein thrombosis (DVT), a blood clot in the deep venous system or veins located deep within your body. It is a serious medical condition because blood clots can break off, traveling to the lungs and potentially causing a life-threatening pulmonary embolism (PE). Understanding the common signs of DVT and pulmonary embolism can help prevent venous complications.
Symptoms of DVT may include:
- Swelling in the leg (or less frequently, the arm)
- Warmth when you touch the affected area
- Skin redness on the legs
- Pain or tenderness in your lower body, such as a cramp
Symptoms of pulmonary embolism may include:
- Sudden shortness of breath
- Chest pain
- Dizziness or fainting
- Coughing, sometimes with blood
If you experience signs of pulmonary embolism, be sure to call 911 immediately or go directly to the nearest emergency room.
What Causes May-Thurner Syndrome?
May-Thurner syndrome results from pressure caused by the right iliac artery placed on the left iliac vein. This pressure disrupts blood flow from the left leg, which can narrow the veins or damage the vein wall, increasing the likelihood of blood clots forming.
May-Thurner Syndrome Risk Factors
Most often, May-Thurner syndrome affects younger women, aged 20 to 40. Certain factors can increase the likelihood that May-Thurner syndrome becomes symptomatic or leads to DVT.
Factors that increase your risk of DVT include:
- Recent surgery or injury: Trauma, surgery, and infection can damage your veins and increase the risk of developing blood clots.
- Blood-clotting disorder: If you or someone in your family has a blood-clotting disorder or a history of blood clots, you are at higher risk for future problems.
- Extended stretches of inactivity: Long periods of inactivity, such as air or car travel, can affect blood flow, increasing your risk of DVT.
- Smoking: Smoking can affect circulation and blood clotting, increasing the risk of deep vein thrombosis.
- Cancer: Some types of cancer, along with cancer treatments like chemotherapy, can make you more likely to develop blood clots.
- Obesity: Obesity or being overweight can strain your veins, increasing your risk of deep vein thrombosis.
- Pregnancy: Your expanding uterus, along with pregnancy-related weight gain, can increase pressure on veins in your legs, making DVT more likely to occur.
- Age: Although anyone of any age can develop DVT, your risk increases as you get older.
- Varicose veins: Having varicose veins and other varicosities may elevate your risk for blood clots.
Pregnancy is an especially high-risk factor for developing May-Thurner syndrome, due to increased blood volume, hormonal changes, and pressure from the growing uterus.
How Is May-Thurner Syndrome Diagnosed?
Diagnosing May-Thurner syndrome can be challenging because symptoms are often absent or mistaken for other vein conditions, which is why a diagnosis is important. Identifying the condition early can help guide targeted May-Thurner syndrome treatment and reduce the risk of future clots.
When consulting a May-Thurner syndrome specialist, the typical diagnostic process usually starts with:
- A physical exam
- A review of your medical history
- Imaging studies to confirm vein compression
These imaging tests can include more common tests, such as an ultrasound, CT scan, and MRI, as well as more advanced tests, such as a venogram or intravascular ultrasound to see inside the blood vessel.
May-Thurner Treatment Options
May-Thurner syndrome treatment depends on symptom severity and whether a blood clot is present. The goal is to improve blood flow, relieve symptoms, and reduce the risk of deep vein thrombosis (DVT).
Treatment to Improve Blood Flow
Many people with symptomatic May-Thurner syndrome benefit from minimally invasive treatment to open the compressed vein and improve circulation.
- Venous angioplasty and stenting: In this minimally invasive procedure, a specialist inserts a catheter with a balloon tip into your vein. Then they inflate the balloon to fully open the vein and insert a tiny mesh tube called a stent to keep the vein open and improve blood flow. Afterward, the balloon is removed.
- Bypass surgery: Some cases may require surgery. A bypass graft can reroute blood around the compressed portion of your iliac vein.
Treatment if a Blood Clot Is Present
If May-Thurner syndrome has led to DVT, treatment may also focus on the clot itself.
- Blood thinners: These medications help prevent the clot from getting larger and reduce the risk of new clots.
- Clot-directed treatment: In some cases, minimally invasive treatment may be recommended to break up or remove the clot and restore blood flow.
Request a Consultation With USA Vein Clinics
USA Vein Clinics performs minimally invasive, office-based treatment for a range of venous conditions, including May-Thurner syndrome. Early evaluation can help prevent serious complications and clarify whether May-Thurner syndrome is contributing to your symptoms.
Our patients at USA Vein Clinics receive:
- Evaluation from experienced vein specialists
- Minimally invasive treatment options
- Access to over 100 clinic locations nationwide
- 24/7 online scheduling
- Bilingual phone support
If you are experiencing unexplained leg swelling or have a history of DVT, early evaluation can help protect your veins.
To get started, schedule an initial consultation with USA Vein Clinics online today.
May-Thurner Syndrome FAQs
What are the early signs of May-Thurner syndrome?
Early signs of May-Thurner syndrome include unexplained left-leg swelling, leg asymmetry, heaviness that worsens with prolonged standing, and subtle skin changes or increasing discomfort over time.
What is the May-Thurner Syndrome life expectancy?
May-Thurner syndrome does not shorten life expectancy, and most people live healthy lives when it is diagnosed and managed. However, complications such as deep vein thrombosis or pulmonary embolism can require immediate treatment.
How to sleep with May-Thurner syndrome?
If you want to know how to sleep with May-Thurner syndrome, try elevating your legs to promote circulation and sleeping on your left side to reduce pressure in the pelvic veins.
Can you have May-Thurner syndrome during pregnancy?
May-Thurner syndrome can occur during pregnancy due to increased blood volume and clotting risk. Sudden left-leg swelling or signs of DVT during pregnancy require immediate medical attention.