Deep Venous Thrombosis

Deep venous thrombosis, also called DVT, refers to a blood clot that has formed in one of the large veins far below the skin.

What is going on in the body?

A deep venous thrombosis is most common in the legs, but it can occur in other parts of the body. A blood clot in a vein blocks the normal flow of blood back to the heart. It also causes the affected vein to become inflamed.

What are the causes and risks of the condition?

A deep venous thrombosis forms when a blood clot in a vein blocks the normal flow of blood back to the heart. Circumstances that increase an individual's risk of developing DVT include:

Diseases and conditions that increase a person's risk for DVT include:

Medicines that can increase the risk for DVT include:

Injuries can also increase a person's risk for DVT. Common injuries linked to DVT include:

Recently, there have been conflicting research reports about the role of long airplane flights in deep venous thrombosis. Some studies showed a relationship between airline travel and an increase in the blood's tendency to form clots. The researchers attributed the increased risk of clot formation to the low pressure, low oxygen, dehydration, and lack of activity on long flights. Another study showed that individuals hospitalized with DVT were four times more likely to have gone on a long trip recently than those treated at the hospital for other conditions. Because of findings like this, deep venous thrombosis is often referred to as "economy class syndrome."

However, other researchers have not found the same relationship. Some suggest that only people with a particular genetic abnormality are at risk for economy class syndrome. More research is needed in this area.