Cardiovascular and Interventional Radiological Society of Europe

Deep vein thrombosis (DVT)


Deep vein thrombosis (DVT) results when a blood clot forms in one of your deep veins, most commonly in your legs. This can lead to a pulmonary embolism, meaning the blood clot has travelled to the lungs and blocked an artery, which is a potentially life-threatening complication.


Patients with DVT may not have any noticeable symptoms. You may, however, experience symptoms in the affected area such as pain, swelling, warmth, changes in your skin colour (such as reddening or turning blue), or swelling of veins that are close to the surface of your body. In addition, you may have a raised body temperature.

Symptoms of a pulmonary embolism vary depending on how big the blood clots are, and on how well your heart is functioning. Patients may have difficulty breathing and experience back pain. Other symptoms include life-threatening reactions such as cardiogenic shock (where the heart is no longer able to pump enough blood) and severe hypoxaemia (low levels of oxygen in the blood).


A doctor can diagnose DVT via ultrasound or CT. It may also be necessary for the doctor to carry out other imaging procedures, such as a CT angiography, to rule out or evaluate the risk of a pulmonary embolism. This involves injecting contrast dye into a vein to highlight the blood vessels carrying blood to and from your lungs, and taking X-ray images of the blood flowing through them.


If the doctor diagnoses a DVT, you should immediately be treated with anti-clotting medication to reduce the risk of both a pulmonary embolism and of post-thrombotic syndrome, a chronic (long-term) complication that can develop after experiencing DVT.

In rare cases, a specialist may have to perform a minimally invasive procedure to instantly reduce the amount of clots. This involves inserting a catheter and using it to inject clot-dissolving medication directly in the clots, or to mechanically break up the clots.