Overview

May-Thurner Syndrome (MTS) is a vascular condition in which the left iliac vein is compressed by the right iliac artery, which results in reduced blood flow as well as an increased risk of developing serious complications such as deep vein thrombosis (DVT) in the left leg.^1,2 Common clinical symptoms of this condition involve pain, skin discolouration and swelling in the leg. In order to prevent serious complications and improve patients’ overall health, early identification and diagnosis is crucial. There are various treatment methods ranging from conservative management (such as compression stockings and anticoagulant medication) to surgical methods to alleviate iliac vein compression and return blood flow back to normal. By educating and understanding MTS we can ensure timely intervention allowing for better outcomes and improved overall health. 

Throughout this article, we will explore what MTS is, any underlying causes, symptoms, and diagnostic techniques as well as the available treatment options to ensure that you are well-informed about MTS and gain valuable insight to aid you in making informed decisions about your vascular health. 

Importance of understanding MTS

As previously mentioned, MTS is a vascular condition characterized by the compression of the left iliac vein, leading to reduced blood flow and an increased risk of blood clots, which can cause DVT in the left leg.^1,2 Therefore, early recognition and diagnosis are crucial to prevent the progression of MTS and avoid life-threatening complications like pulmonary embolism. Additionally, understanding MTS can help in selecting appropriate treatment methods, such as surgical procedures, conservative management, and catheter-based interventions, thereby improving outcomes and overall well-being.³
Raising awareness among both the general public and healthcare professionals is essential for timely interventions and enhancing the quality of life for those affected by MTS.

Anatomy and pathophysiology of MTS - iliac vein compression

In order to effectively identify and manage MTS, addressing and understanding iliac vein compression is essential not only to improve the patient's overall health and well-being but to also prevent life-threatening blood clots.

Figure 1 Anatomy of iliac blood vessels.

The area in a yellow circle shows the right common iliac artery (red) as it crosses and compresses the left common iliac vein (blue). Modification of image from Grey’s Anatomy (out of copyright). 

Iliac vein compression occurs when the common iliac vein, a major blood vessel in the pelvic region, becomes narrowed or constricted.⁴ This condition often arises from a physical anomaly where the right iliac artery compresses the left iliac vein against the spine (refer to Figure 1). The resulting pressure build-up in the affected vein can reduce blood flow and lead to swelling.⁴ Iliac vein compression can have serious consequences, potentially leading to the development of MTS. 

What causes MTS?

According to the Cleveland Clinic and the Vascular Institute of the Rockies, MTS is not a genetic condition and cannot be inherited from parents. While the exact causes remain unclear, several factors can increase the likelihood of developing MTS, including:^2,3

• Being assigned female at birth (AFAB)
• Recently giving birth
• Having more than one child
• Taking hormonal birth control
• Having a condition that causes your blood to clot
• Being dehydrated
• Sitting for long periods

Signs and symptoms of MTS

Common clinical presentations

The signs and symptoms of MTS can vary among individuals, but common clinical presentations can aid in its diagnosis. Patients with MTS often exhibit tenderness and swelling in the lower left leg due to reduced blood flow, along with severe pain.^2,3 Additionally, some patients may experience skin discolouration, visible varicose veins, and non-healing wounds or ulcers on the lower left leg, which can indicate complications of MTS.⁵ Recognizing these common clinical signs is essential for prompt diagnosis and appropriate treatment to prevent complications and improve the overall quality of life for patients.

Diagnostic imaging techniques 

Diagnostic imaging techniques can be essential to diagnose MTS: Non-invasive imaging techniques such as computed tomography venography (CTV), Doppler ultrasounds and magnetic resonance venography (MRV) all play a crucial role in visualising the iliac vein and can detect any compression or abnormalities. By using sound waves, the Doppler ultrasound identifies narrowing in the veins caused by iliac vein compression, while CTV and MRV use computed tomography (CT) and magnetic resonance imagining (MRI) scans in order to create a detailed scan of the veins.⁴ 

Using these diagnostic imaging techniques, healthcare professionals can accurately and rapidly diagnose MTS and establish appropriate treatment to prevent serious complications. 

The impact of MTS on blood circulation

MTS can significantly impact blood circulation, leading to serious cardiovascular health consequences. In this condition, the left iliac vein is compressed by the overlying right iliac artery, restricting blood flow in the affected vein and altering circulation patterns. This restriction can cause various complications, including increased pressure within the left iliac vein, blood pooling in the leg, and difficulty in returning blood to the heart. Additionally, impaired blood circulation can lead to the formation of blood clots, which may result in severe complications such as pulmonary embolism if the clots travel to the lungs.^6,7

Challenges in diagnosing MTS

Diagnosing MTS can be challenging due to several factors: One major difficulty is the overlap of MTS symptoms with those of other conditions, such as varicose veins and DVT, which can lead to delays in diagnosis or misdiagnosis. Additionally, some individuals with MTS may be asymptomatic, making it difficult to recognize the condition until serious complications occur.⁸ 

To overcome these challenges, early and comprehensive evaluations are essential for the timely identification and appropriate treatment of MTS.

Treatment approaches for MT

Conservative management and its limitations

One of the primary treatment methods for MTS is conservative management, particularly for asymptomatic or mild cases. This approach aims to alleviate symptoms, prevent blood clots, and improve blood flow. It typically involves the use of anticoagulant medication to reduce the risk of DVT and compression stockings to promote blood flow back to the heart. A key component of conservative management is implementing lifestyle changes, such as avoiding prolonged sitting or standing and engaging in regular exercise.⁹ 

While conservative management can be highly effective, it may have limitations in more advanced cases of MTS. In such instances, other treatment options, including surgical procedures and catheter-based interventions, may be necessary to address iliac vein compression and improve blood flow.⁴ The most effective treatment approach should be discussed with a healthcare professional, considering the patient's condition, symptoms, and overall health.

Catheter-based interventions and endovascular procedures

For more advanced cases of MTS, catheter-based interventions and endovascular procedures are highly effective in addressing iliac vein compression and improving blood flow, while being minimally invasive. During these procedures, a catheter is guided through the blood vessels to the site of compression. A stent or balloon angioplasty is then used to expand the compressed vein, maintain vessel patency, and prevent re-narrowing.⁹

These procedures not only reduce the risk of serious complications such as DVT but also restore normal blood flow. Compared to traditional surgery, catheter-based interventions offer benefits such as reduced hospital stay, faster recovery, and lower risk of complications. The success of these interventions depends on the patient's overall health and the extent of iliac vein compression.

Surgical options and considerations

Another treatment method for more serious cases of MTS is surgery, particularly when other procedures have not been effective. Surgical procedures for MTS directly address the anatomical abnormality causing iliac vein compression. Venous bypass surgery, a common technique, uses a graft to bypass the compressed vein and restore normal blood flow. Another technique is venous transposition, where the iliac vein is moved to a new position to relieve compression.⁶ While surgical options can be very effective in treating iliac vein compression, they are more invasive compared to catheter-based procedures and typically require longer recovery periods and hospital stays.⁹

Summary

May-Thurner Syndrome (MTS) is a vascular condition where the right iliac artery compresses the left iliac vein, leading to reduced blood flow and an increased risk of complications such as deep vein thrombosis (DVT) in the left leg. Early detection and diagnosis are crucial to prevent serious complications and improve patient outcomes. Recognizing common clinical symptoms and using appropriate diagnostic imaging techniques ensure accurate diagnosis. However, due to symptom overlap with other conditions, diagnosing MTS can be challenging. Various treatment approaches, including conservative management, surgical options, and catheter-based interventions, can effectively address MTS and its potential complications. Further research and understanding of MTS can enhance management strategies and improve the quality of life for patients affected by this condition.