A person with a deep venous thrombosis has a blood clot in a vein, usually in the leg.

Thrombosis is a term used to describe the formation of a blood clot. A deep venous thrombosis is a blood clot that forms in a large, deep vein of the leg, thigh or pelvis. Rarely, a deep venous thrombosis can form in the arms.

About 250,000 people are admitted to the hospital for deep venous thrombosis every year in the US.