INATE - INvestigators Against ThromboEmbolism
The facts on post-thrombotic syndrome
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What is post-thrombotic syndrome?
How do I know if I have post-thrombotic syndrome?
Preventing post-thrombotic syndrome
Treating post-thrombotic syndrome
Preventing is better than cure

Venous thrombosis is the development of a blood clot in a vein. Sometimes, thrombosis leads to serious short-term and long-term effects. A possible short-term effect is pulmonary embolism, in which the blood clot breaks into pieces, travels to the lungs and blocks the flow of blood through the lungs. Long-term effects are known as post-thrombotic syndrome. If you have had a venous thrombosis, you may be at risk of developing post-thrombotic syndrome.

What is post-thrombotic syndrome?
Post-thrombotic syndrome is the name used to describe the long-term effects that can occur after you have had a venous thrombosis of the deep veins of the leg. It is caused by damage to the veins, resulting in higher than normal blood pressure. This increased pressure on the vein walls can damage the valves, which normally work to keep blood flowing properly through your veins. Poor blood flow can lead to pain, swelling and leg ulcers, which are some of the symptoms of post-thrombotic syndrome. Post-thrombotic syndrome can cause serious long-term ill health, poor quality of life, and increased costs for the patient and the healthcare system.

Post-thrombotic syndrome is common in people who have had thrombosis, whether they are young or old. Generally, 1 out of 3 people who have had thrombosis in the legs will develop some post-thrombotic symptoms within 5 years. Most episodes of post-thrombotic syndrome will occur within 2 years of the thrombosis. People who have thrombosis more than once (recurrent thrombosis) are at higher risk for post-thrombotic syndrome. Thrombosis can go unnoticed, so it is sometimes possible to have post-thrombotic syndrome without being diagnosed with thrombosis first.


How do I know if I have post-thrombotic syndrome?
Post-thrombotic syndrome is difficult to diagnose because it sometimes looks like acute thrombosis. The symptoms can be mild, moderate or severe. If you notice any of the following symptoms in your leg, it may mean that you have post-thrombotic syndrome:

  • heaviness
  • pain
  • cramps
  • itchiness
  • numbness or tingling
  • swelling
  • hardened or darkened patches of skin
  • dilatation of veins
  • redness
  • leg ulcers


It is important to remember that these signs and symptoms are not specific to post-thrombotic syndrome and could be caused by other factors, such as poor circulation in smaller veins, advanced age, weight gain or leg injury. If you have these signs and symptoms but have never been diagnosed with thrombosis, your doctor may perform some tests in addition to a standard examination. These tests will help your doctor to determine if you have post-thrombotic syndrome following an earlier undiagnosed thrombosis or if you have a new thrombosis. These tests include:

  • compression ultrasound – a simple and easy test to determine if there is a clot in your veins. Compression ultrasound is generally the first type of test that your doctor will use because it works best soon after thrombosis has occurred
  • continuous-wave Doppler ultrasound – this test is a simple and fast way to detect whether the valves in your veins are working properly and the blood is flowing normally
  • color duplex scanning – uses color scans to visualize blood vessels and uses Doppler ultrasound to detect the direction of blood flow. This test takes longer than Doppler ultrasound but it can also measure how much damage there is to the veins and exactly where the damage is


Preventing post-thrombotic syndrome
There are several things that you and your doctor can do to reduce your risk of post-thrombotic syndrome. The best way to avoid post-thrombotic syndrome is to prevent thrombosis from occurring in the first place.

If you are at high risk for thrombosis (if you are having orthopedic surgery, for example), you can reduce your risk by limiting the amount of time spent in bed and by wearing elastic compression stockings. Drugs that prevent thrombosis after surgery are usually recommended, and include:

  • low-molecular-weight heparin (LMWH) – works quickly and can be injected at home under the skin once or twice a day. It is very effective in preventing blood clots
  • unfractionated heparin (UFH) – is an older form of heparin and is given by injection under the skin, usually twice a day. Although it will prevent blood clots in the leg, it is not as effective as LMWH
  • oral anticoagulants, sometimes called blood-thinner pills, have been used for many years to prevent thrombosis, but can take around 3 days to become effective
  • pentasaccharide can also prevent thrombosis and has recently become available in some countries. Pentasaccharide is still being tested in further clinical studies


If you have thrombosis, it is important to be treated quickly and effectively with UFH or LMWH, followed by oral anticoagulants. In most countries, the preferred treatment is usually LMWH. It is also important to prevent thrombosis from recurring because people with recurrent thrombosis are at high risk of post-thrombotic syndrome. To prevent the recurrence of thrombosis, your doctor may recommend that you wear elastic compression stockings for at least 6 months and also receive oral anticoagulants, UFH or LMWH for up to 6 months.


Treating post-thrombotic syndrome

Most people with post-thrombotic syndrome receive standard treatment,
which is mainly aimed at preventing or treating leg ulcers:


  • wearing elastic compression stockings
  • exercising regularly
  • elevating your leg(s) while resting
  • regular visits to your doctor

Although the treatment of post-thrombotic syndrome with drugs has been studied, they are not usually used. If standard treatment is not adequate, and particularly if you have leg ulcers, your doctor may consider surgery. Your doctor will carefully weigh the risks and benefits of surgery to decide whether this is a suitable treatment option for you.


Prevention is better than cure
The outcome of treatment for people with severe post-thrombotic syndrome was previously thought to be poor. It is now believed that, with standard treatment and careful supervision, symptoms improve or remain stable in half of all people with post-thrombotic syndrome. However, the best way to treat post-thrombotic syndrome is to prevent thrombosis from occurring in the first place, a case where prevention really is better than cure.


Bernardi E and Prandoni P. The post-thrombotic syndrome. Current Opinions in Pulmonary Medicine 2000;volume 6:pages 335-42.

Janssen MCH et al. The post-thrombotic syndrome: a review. Phlebology 1996;volume 11:pages 86-94.

Prandoni P et al. The long-term clinical course of acute deep venous thrombosis. Annals of Internal Medicine 1996;volume 125:pages 1-7.

Ruckley CV. Socioeconomic impact of chronic venous insufficiency and leg ulcers. Angiology 1997;volume 48:67-9.


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