The disease known as May Thurner syndrome (MTS) impairs left leg blood flow. It happens when the left iliac vein, which drains blood from the left leg, is compressed by the right iliac artery, which feeds blood to the right leg. This may result in left leg edema, discomfort, and blood clots.
The physical location of the left iliac vein and right iliac artery is the primary cause of MTS. In the lower abdomen, the left iliac vein is crossed by the right iliac artery, which may push against it and cause its lumen to shrink. This may lead to an increase in vein pressure and turbulence as well as a decrease in left iliac vein blood flow. Deep vein thrombosis (DVT), another name for blood clots that may develop in the left leg, can result from this.
Some factors that may increase the risk of developing MTS or DVT include:
Being female, as women have a smaller pelvic diameter and a higher incidence of MTS.
Being pregnant, as pregnancy can increase the blood volume and the pressure on the pelvic veins.
Having a history of trauma, surgery, or catheterization in the pelvic area, as these can damage or inflame the veins.
Having a genetic or acquired blood disorder that makes the blood more prone to clotting, such as factor V Leiden or antiphospholipid syndrome.
Having other conditions that affect the blood flow or the veins, such as obesity, smoking, cancer, or heart failure.
Many people with MTS do not have any symptoms, and may not be aware of their condition until they develop a DVT. The symptoms of MTS and DVT may include:
Swelling, pain, heaviness, or cramping in the left leg, especially in the calf or thigh.
Redness, warmth, or discoloration of the skin on the left leg.
Varicose veins or spider veins on the left leg.
Ulcers or sores on the left leg.
If a blood clot breaks off and travels to the lungs, it can cause a life-threatening condition called pulmonary embolism (PE). The symptoms of PE may include:
Sudden shortness of breath or difficulty breathing.
Chest pain or tightness, especially when breathing or coughing.
Coughing up blood or bloody sputum.
Rapid or irregular heartbeat.
Dizziness, fainting, or loss of consciousness.
MTS can be diagnosed by a physical examination and medical history, as well as some tests and imaging studies. The diagnosis may include:
A blood test to check for the levels of a protein called D-dimer, which is released when a blood clot dissolves. A high level of D-dimer may indicate the presence of a DVT or a PE.
A Doppler ultrasound to measure the blood flow and the diameter of the veins in the legs. A Doppler ultrasound can detect any narrowing, obstruction, or clotting in the veins.
A venogram to inject a contrast dye into the veins and take X-ray images of the veins. A venogram can show the exact location and extent of the compression or clotting in the veins.
A computed tomography (CT) scan or a magnetic resonance imaging (MRI) scan to produce detailed images of the veins and the surrounding structures. A CT scan or an MRI scan can confirm the diagnosis of MTS and rule out other causes of leg swelling or pain.
The treatment of MTS aims to restore the blood flow in the left iliac vein, prevent or dissolve the blood clots, and prevent the complications. The treatment options include:
Medication to thin the blood and prevent or treat the blood clots. Medication may include anticoagulants, such as warfarin or heparin, or thrombolytics, such as streptokinase or tissue plasminogen activator (tPA).
Compression stockings to apply pressure on the legs and improve the blood circulation. Compression stockings can reduce the swelling, pain, and risk of ulcers in the legs.
Stenting to insert a metal mesh tube into the left iliac vein and expand its lumen. Stenting can relieve the compression and improve the blood flow in the vein.
Angioplasty to inflate a balloon inside the left iliac vein and widen its lumen. Angioplasty can be done before or after stenting to enhance the results.
Surgery to bypass or remove the compressed or clotted segment of the left iliac vein. Surgery may be needed if the other treatments are ineffective or contraindicated.
There is no specific way to prevent MTS, as it is mainly caused by the anatomical position of the right iliac artery and the left iliac vein. However, there are some steps that can be taken to reduce the risk or severity of DVT, such as:
Avoiding prolonged sitting or standing, and moving or stretching the legs regularly.
Drinking plenty of fluids and staying hydrated.
Losing weight and maintaining a healthy weight.
Quitting smoking and avoiding exposure to secondhand smoke.
Taking medication or wearing compression stockings as prescribed by the doctor.
Seeking medical attention if there are any signs or symptoms of DVT or PE.
