A thrombosis is a blood clot. The clot may block a blood vessel, causing potentially serious health effects. A deep vein thrombosis (DVT) is a blood clot that forms in the deep veins of the leg. A deep vein thrombosis in the thigh carries a risk ...

What is deep vein thrombosis? Deep vein thrombosis (DVT) is a blood clot (thrombus) in a deep vein, usually in the legs. Clots can form in superficial veins and in deep veins. Blood clots with inflammation in superficial veins (called superficial thrombophlebitis or phlebitis) rarely cause ...