Venous thromboembolism (VTE) refers to a blood clot that starts in a vein. It is the third leading vascular diagnosis after heart attack and stroke, affecting between 300,000 to 600,000 Americans each year. There are two types:
- Deep vein thrombosis (DVT) Deep vein thrombosis is a clot in a deep vein, usually in the leg. DVT sometimes affects the arm or other veins.
- Pulmonary embolism (PE) A pulmonary embolism occurs when a DVT clot breaks free from a vein wall, travels to the lungs and then blocks some or all of the blood supply. Blood clots originating in the thigh are more likely to break off and travel to the lungs than blood clots in the lower leg or other parts of the body.
What causes venous thromboembolism?
The most common triggers for venous thromboembolism are surgery, cancer, immobilization and hospitalization.
Deep vein thrombosis forms in the legs when something slows or changes the flow of blood. In women, pregnancy and the use of hormones like oral contraceptives or estrogen for menopause symptoms can also play a role.
Certain groups are at higher risk for clotting:
- Older people
- People who are obese or overweight
- People with cancer or other conditions (including autoimmune disorders such as lupus)
- People whose blood is thicker than normal because their bone marrow produces too many blood cells
Genetic causes of excessive blood clotting are also important. This happens when there are changes in the genetic code of some proteins needed for clotting, or proteins that work to dissolve blood clots in the body.
Venous thromboembolism is most common in adults 60 and older, but it can occur at any age. VTE is rare in children, though.
Read more about VTE risk factors.
The future of venous thromboembolism
Pulmonary embolism is the most common preventable cause of death among hospital patients in the United States, and yet venous thromboembolism in general – and pulmonary embolism in particular – is often overlooked as a major public health problem.
The potential public health benefit of preventing VTE is considerable. Data from randomized trials involving general surgical patients suggest that adequate prevention measures in high-risk patients can prevent VTE in one of 10 patients – and save the life of about one of 200 patients.
Also in this section:
- Printable information sheet: What is VTE? (PDF)
- What is excessive blood clotting (hypercoagulation)?
- Family history and heart disease