Overview

May-Thurner Syndrome is a vascular condition in which a vein in the pelvis becomes compressed by a nearby artery. This can restrict blood flow through the affected vein and increase the risk of developing deep vein thrombosis (DVT).

The condition most commonly involves compression of the left common iliac vein by the overlying right common iliac artery. However, the underlying anatomy and severity can vary between individuals.

May-Thurner Syndrome does not always cause symptoms. When symptoms occur, they may include swelling, pain or heaviness in the leg, particularly when associated with DVT.

At the Supreme Vascular and Interventional Clinic, Dr. Manish Taneja provides specialist assessment for selected patients with venous conditions, including assessment of May-Thurner Syndrome and appropriate treatment options.

What Is May-Thurner Syndrome?

May-Thurner Syndrome, also known as iliac vein compression syndrome, occurs when an artery presses against an adjacent iliac vein.

The iliac veins are large blood vessels that return blood from the legs and pelvis towards the heart. When an iliac vein is significantly compressed, normal venous drainage may become restricted.

Over time, this may contribute to changes within the vein and increase the risk of blood clot formation.

The condition is most commonly associated with compression of the left common iliac vein, although variations in anatomy can occur.

Importantly, anatomical compression does not necessarily mean that a person has symptomatic May-Thurner Syndrome. Treatment decisions depend on symptoms, venous obstruction, associated complications and the individual's overall clinical situation.

What Causes May-Thurner Syndrome?

May-Thurner Syndrome is primarily related to the anatomy of the pelvic blood vessels rather than something a person develops because of a single lifestyle factor.

In the typical anatomical pattern, the right common iliac artery crosses over and compresses the left common iliac vein against the underlying spine.

This compression can interfere with venous blood flow from the left leg.

Risk Factors

You stand a greater chance of developing May Thurner Syndrome if:

• You have genetic predispositions.
• You suffer from potential triggers that may cause your blood to clot.
• You are dehydrated.

The likelihood of developing symptoms or complications may also be influenced by other factors that increase the risk of DVT, including:

• Prolonged immobility
• Recent surgery or hospitalisation
• Previous DVT
• Pregnancy
• Certain hormone-based medications
• Cancer and some cancer treatments
• Blood-clotting disorders
• Other conditions that increase the risk of venous thrombosis

Symptoms of May-Thurner Syndrome

Some people with May-Thurner Syndrome have no noticeable symptoms.

When symptoms occur, they may include:

• Swelling in one leg, particularly the left leg
• Tenderness
• Leg pain or discomfort
• A feeling of heaviness or fullness in the leg
• Leg fatigue
• Skin changes associated with chronic venous congestion
• Skin that feels warm
• Redness or changes in skin color
• Symptoms that become more noticeable after prolonged standing or activity

If May-Thurner Syndrome is associated with DVT, symptoms may develop more suddenly and can include significant swelling, pain, warmth or tenderness in the affected leg.

Symptoms alone cannot confirm May-Thurner Syndrome because similar symptoms can occur with other venous and musculoskeletal conditions.

May-Thurner Syndrome and Deep Vein Thrombosis

One of the most important clinical associations with May-Thurner Syndrome is deep vein thrombosis (DVT). When an iliac vein is significantly compressed, venous blood flow may become slower or restricted. This can contribute to the development of a blood clot in the affected leg or pelvic veins.

A DVT can cause:

• Leg swelling
• Pain or tenderness
• Warmth
• Redness or changes in skin colour
• A feeling of heaviness in the affected limb

A blood clot can also potentially travel to the lungs and cause a pulmonary embolism (PE). However, not everyone with May-Thurner Syndrome develops DVT, and not everyone with DVT has May-Thurner Syndrome.

May Thurner Syndrome arises when the right iliac artery compresses the left iliac vein, which transports blood from the legs and pelvis to the heart. The pressure impacts blood flow, resulting in narrowing and scarring. This increases your chances of developing deep vein thrombosis in the leg, a condition that can be life-threatening.

Some with MTS have no symptoms, but over time, can develop the following venous conditions.

How Is May-Thurner Syndrome Diagnosed?

Diagnosis begins with understanding the patient's symptoms, medical history and any previous history of DVT or other venous problems.

Because the iliac veins are located deep within the pelvis, the affected area may require specialised imaging to assess blood flow and identify venous compression.

Depending on the circumstances, investigations may include:

• Duplex ultrasound
• CT venography
• MR venography
• Conventional venography
• Intravascular ultrasound (IVUS) in selected patients

The appropriate imaging depends on the suspected cause, symptoms and clinical findings.

A specialist may also assess whether the anatomical compression is actually contributing to the patient's symptoms or venous disease rather than simply being an incidental finding.

Does May-Thurner Syndrome Always Require Treatment?

Not everyone with anatomical iliac vein compression requires treatment.

Some people have compression without symptoms or clinically significant obstruction and may not require an intervention.

Treatment is more likely to be considered when May-Thurner Syndrome is associated with significant symptoms, venous obstruction, recurrent DVT or other clinically important complications.

The decision depends on the individual's symptoms, imaging findings, history of thrombosis and overall risk profile.

May-Thurner Syndrome Treatment

Treatment depends on whether the condition is causing symptoms, restricting venous blood flow or contributing to complications such as DVT.

Treating Deep Vein Thrombosis

If May-Thurner Syndrome is associated with DVT, treatment may include anticoagulation, medical management, and, for selected patients, minimally invasive treatments such as catheter-directed thrombolysis to remove or reduce the clot. Where significant iliac vein compression is contributing to venous obstruction, venous angioplasty and stenting may also be considered. The appropriate approach depends on the extent of the clot, degree of venous obstruction, symptoms and overall clinical condition.

Venous Angioplasty and Stenting

For selected symptomatic patients with significant iliac vein obstruction, venous angioplasty and stenting may be considered.

A specialised catheter is used to access the affected vein, assess the area of obstruction and, where appropriate, place a stent to help maintain an open channel for blood flow.

Whether venous stenting is appropriate depends on the degree of obstruction, symptoms, associated thrombosis and other clinical factors.

Treating Pulmonary Embolism

Treatment for pulmonary embolism depends on its severity and effect on the heart and lungs. Anticoagulation is commonly used, while selected patients may require thrombolysis or minimally invasive catheter-based treatment such as mechanical embolectomy to remove or reduce the clot. Surgical treatment may be considered in certain severe cases.

Treatment of Underlying Venous Disease

Patients may also require management of other contributing venous conditions or complications.

The overall treatment plan should address both the immediate problem, such as DVT, and the underlying venous obstruction where clinically appropriate.

When May Venous Stenting Be Considered?

Venous stenting may be considered for selected patients when May-Thurner Syndrome causes clinically significant venous obstruction or symptoms.

Factors that may be considered include:

• Persistent or significant symptoms
• Evidence of significant iliac vein obstruction
• Previous or recurrent DVT
• Persistent venous outflow obstruction following treatment of DVT
• Imaging findings that correlate with the patient's symptoms
• The individual's overall health and risk factors

Not every patient with May-Thurner anatomy needs a stent. Specialist assessment is important to determine whether the compression is clinically significant and whether intervention is appropriate.

How Is the Right Treatment Chosen?

Treatment decisions depend on the patient's individual presentation.

A specialist may consider:

• Whether the patient has symptoms
• Whether there is an acute or previous DVT
• The severity of venous obstruction
• The location and extent of the compression
• Results from vascular imaging
• Risk factors for recurrent thrombosis
• Previous treatment and response
• The patient's overall health

The aim is to determine whether observation, medical management or an interventional approach is most appropriate.

When Should I See a Specialist for May-Thurner Syndrome?

Specialist assessment may be appropriate if you have unexplained swelling or discomfort in one leg, particularly if symptoms are persistent or there is a history of DVT.

Patients diagnosed with May-Thurner Syndrome may also benefit from specialist assessment when imaging has identified iliac vein compression and there is uncertainty about whether it requires treatment.

A specialist can assess the relationship between the anatomical compression, symptoms and venous blood flow before discussing potential treatment options.

May-Thurner Syndrome in Singapore

Patients in Singapore with suspected or diagnosed May-Thurner Syndrome can seek specialist assessment to understand whether iliac vein compression is contributing to their symptoms or risk of venous thrombosis.

At the Supreme Vascular and Interventional Clinic, Dr. Manish Taneja provides specialist assessment for selected patients with venous conditions, including evaluation of iliac vein compression and potential minimally invasive treatment where appropriate.

Assessment may include reviewing symptoms, previous DVT or venous treatment, relevant imaging and the extent of venous obstruction before discussing whether further treatment is required.

Frequently Asked Questions About May-Thurner Syndrome