Deep vein thrombosis (DVT) is a blood clot that develops within a deep vein in the body, usually in the leg.
Blood clots that develop in a vein are also known as venous thrombosis.
DVT usually occurs in a deep leg vein, a larger vein that runs through the muscles of the calf and the thigh.
It can cause pain and swelling in the leg and may lead to complications such as pulmonary embolism. This is a serious condition that occurs when a piece of blood clot breaks off into the bloodstream and blocks one of the blood vessels in the lungs.
DVT and pulmonary embolism together are known as venous thromboembolism (VTE).