Deep vein thrombosis or DVT is caused by a thrombus or blood clot that forms in a deep vein. Blood clots form when blood hardens and turns from a liquid to a solid. When a blood clot breaks off and travels in the blood it is referred to venous thromboembolism (VTE).
Symptoms. Deep vein thrombosis affects mainly the large veins of the lower leg and thigh, usually on one side of the body. The clot can block blood flow and cause changes in skin colour (redness), pain, skin that feels hot to the touch and inflammation.