Iliac vein thrombosis occurs when a blood clot prevents blood from moving through your iliac vein. This blockage may cause pain in your legs and pelvis.

According to the Centers for Disease Control and Prevention, an estimated 900,000 Americans per year experience blood clots, and clots contribute to almost 100,000 deaths per year.

A blood clot in the iliac vein is known as iliac vein thrombosis. This type of blood clot can cause leg and pelvic pain because blood cannot pass through the vein.

It’s important to be aware of the risk factors for and symptoms of blood clots because these obstructions can become life threatening.

The common iliac vein is made up of the internal and external iliac veins.

The internal iliac vein drains blood from your pelvic area, while the external iliac vein connects to your femoral veins. The external iliac vein is located in your lower leg and passes through your pelvis.

Blood clots that occur in any of these blood vessels are classified as iliac vein thrombosis.

Symptoms of iliac vein thrombosis include:

  • swelling and discomfort in your legs
  • skin ulcers (sores)
  • lower back pain
  • pelvic pain
  • darkening of skin on your legs

Discomfort from iliac vein thrombosis may be constant, or it may come and go. It may also be worse with physical activity, since blood flow to the legs may increase during activity and the blood may have trouble moving past the blockage.

Massive blockages due to clots in the iliac vein can also cause phlegmasia alba and cerulea dolens, which are emergency conditions.

“Thrombosis” is the medical term for blood clots that form in blood vessels. These clots can form in either veins or arteries, preventing blood flow and leading to serious conditions such as a sudden hemorrhage, stroke, or heart attack. Acute thromboses are actually the leading cause of death in developed countries.

People may experience pain in a particular part of the body, depending on the location of the blood clot. For example, those with intracardiac thrombosis may experience chest pain along with trouble breathing.

Thrombosis has many similar features to an embolism, but these are two different conditions. You can learn more about how they are different here.

Risk factors for thrombosis include:

Doctors may order blood work to determine whether you have risk factors for thrombosis. But thrombosis is typically identified through medical imaging such as CT and MRI scans.

Depending on the type of thrombosis in question, healthcare professionals may also use ultrasound or other types of imaging in diagnosis.

In addition to taking a health history and performing a physical exam, your doctor will likely recommend medical imaging to help them diagnose iliac vein thrombosis.

Iliac vein thrombosis can be detected with:

  • ultrasound
  • CT scans
  • MRI scans

Your doctor will likely want to determine whether any underlying conditions, such as May-Thurner syndrome, are contributing to blood clot formation. They may order blood tests to help determine whether you have any other conditions.

About May-Thurnere syndrome

In addition to the risk factors for thrombosis listed above, May-Thurner syndrome may cause pressure and constriction of the iliac vein. This is a condition in which the left iliac vein narrows due to pressure from the right iliac artery. You can learn more about it here.

People who have May-Thurner syndrome and not thrombosis typically experience symptoms in only their left leg.

Was this helpful?

In general, treatment for thrombosis often relies on anticoagulant medications. Some of the more commonly used medications are warfarin, low molecular weight heparin, dabigatran, rivaroxaban, and apixaban.

As a general rule, you can expect to take these medications for at least several months after the blood clot has disappeared to help prevent thrombosis from recurring.

In addition to anticoagulant medications, treatment for iliac vein thrombosis may involve surgery to remove the blood clots. Your doctor may also advise the use of compression stockings or other compression devices.

To help reduce the chance that thrombosis will happen again, you can expect to continue a treatment plan and monitoring for at least several months after thrombosis is no longer present.

Iliac vein thrombosis can block blood flow, causing leg and pelvis pain. People with iliac vein thrombosis need prompt treatment to prevent potentially life threatening conditions from developing.

If you believe that you or someone else may have thrombosis of any kind, it’s important to seek medical assistance right away.