Leg Thrombosis: A blood clot in one of the leg veins

Thirty thousand people per year develop a venous thrombosis, such as a thrombosed leg or pulmonary embolism (2020). To prevent complications and chronic complaints, it is important to seek help quickly if you suspect a thrombosed leg. It is important to recognize the symptoms. What are the causes of thrombosis, the symptoms, how is it treated and what is the prognosis? You can request a free Anticoagulation Card via the Thrombosis Foundation website.

Article content

  • Thrombosis
  • Thrombotic leg, deep vein thrombosis (DVT)
  • Causes of thrombosis in the leg
  • Symptoms of thrombosis leg
  • Pulmonary embolism
  • Diagnosis of thrombosis leg
  • Treatment of thrombosis leg
  • Prognosis of thrombotic leg and post-thrombotic syndrome
  • CAVA study (CAtheter Versus Anticoagulation)
  • Anticoagulation pass



Thrombosis is a blood clot, also called a thrombus, in an artery or vein. Usually in a vein. In thrombosis you can distinguish between thrombosis due to vein inflammation (thrombophlebitis) and thrombosis without inflammation. The latter form is the most common, especially in deep thrombosis and is called: phlebothrombosis. Thrombosis can occur in various places in the body, but there is a preference for the legs, hence the term thrombosis leg.

Thrombotic leg, deep vein thrombosis (DVT)

If a clot forms in the deep veins of the leg, it is called deep vein thrombosis (DVT). There is a chance that part or all of a clot may detach. It can enter the bloodstream through the heart and if it enters a blood vessel to the lungs, it can cause a blockage that can be fatal.

Causes of thrombosis in the leg

Deep vein thrombosis is often caused by a combination of factors: the blood flows slowly through a vein, the tendency to clot is increased and the wall of the vein is damaged. The blood flow can be slowed down if someone has been sitting still for too long (think of a plane trip), but it can also happen if you have to lie in bed for a long time due to circumstances. Other possible causes: a tumor, if the unborn child compresses a vein during pregnancy. A fracture of the leg can also slow blood circulation and cause a clot. After an accident, a surgical procedure, a malignant tumor or during pregnancy, the blood can clot more quickly. There may also be a congenital disease.

Symptoms of thrombosis leg

If a blood clot is in a deep vein in the legs or pelvis, you may suffer from the following symptoms:

  • Thick ankles;
  • The leg hurts and is tender, warm;
  • The leg is swollen;
  • The skin may be tight, shiny;
  • Veins under the skin may be swollen.

But beware, half of the thrombosed legs show no complaints at all!

Pulmonary embolism

In approximately twenty percent of cases, deep venous thrombosis leads to pulmonary embolism. Symptoms of a pulmonary embolism include chest pain that worsens when breathing and a person is short of breath. If the supply of blood to the lungs is completely obstructed, a very dangerous situation arises. Thrombosis can cause damage to the vein that does not disappear, varicose veins can develop. The term venous thromboembolism is also used for deep vein thrombosis and pulmonary embolism: VTE.

Diagnosis of thrombosis leg

The symptoms that occur with deep vein thrombosis resemble those of other conditions such as subcutaneous inflammation of connective tissue. The doctor will therefore have to do a number of tests to confirm the diagnosis. A Doppler ultrasound can measure the flow of blood through the veins. Blood tests can determine how quickly the blood clots.

Treatment of thrombosis leg

The treatment used in most hospitals is direct administration of a blood thinner, first via injections, later in pill form (acenocoumarol, marcoumar). A support stocking will have to be worn for the first two years after the thrombosis. The chance of developing a thrombotic leg again is quite high and twenty to fifty percent of people will later develop post-thrombotic syndrome.

Prognosis of thrombotic leg and post-thrombotic syndrome

If deep vein thrombosis is discovered quickly, it can usually be treated well with thrombolytics and anticoagulants. Post-thrombotic syndrome (PTS) can develop in the longer term as a result of a deep venous thrombosis. The clot can affect the valves in the vein and if they no longer work properly, the blood can flow back more easily. The pressure on the veins and small capillaries increases and the blood stagnates in parts of the veins. This can cause inflammatory reactions and then there is post-thrombotic syndrome. Complaints: heavy, tired feeling in the body part, cramps may occur, fluid retention (edema), brown discoloration of the skin, eczema and varicose veins. Furthermore, the skin may look thin and shiny, there may be white discolouration on the skin and sometimes there may be wounds that are difficult to heal. The latter is also called an open leg. Post-thrombotic syndrome can usually be prevented through proper treatment, but once it occurs, it can never be completely cured.

CAVA study (CAtheter Versus Anticoagulation)

In a large-scale study (led by Maastricht UMC+), treatment methods for the prevention of post-thrombotic syndrome were compared. The research was conducted in fifteen hospitals in the Netherlands. The study compared treatment methods for the prevention of post-thrombotic syndrome. On November 27, 2019, the results of the study were published in the scientific journal Lancet Haematology. The results were not in line with expectations. A new catheter-guided technique to tackle acute thrombosis in the groin resulted in a smaller reduction in post-thrombotic syndrome than expected. There would be almost no difference with the standard treatment: anticoagulant medication and a support stocking.

Anticoagulation pass

If you use blood thinners, you can request a (free) Anticoagulation Pass via the website of the Thrombosis Foundation. With this card you always have the important information with you and you can prevent bleeding and incorrect treatment. Take the card with you to the doctor, specialist and dentist or when you pick up medication at the pharmacy or drugstore. But also if you visit the pedicure, dental hygienist or physiotherapist or get a vaccination from the GGD.

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