What are deep vein thrombosis (DVT) and pulmonary embolism?
There are two systems of veins in the legs – the important deep veins (which carry most of the blood up the legs towards the heart) and the less important superficial veins just under the skin (which can form varicose veins). Deep vein thrombosis (DVT) means thrombosis (clotting) of blood in the deep veins of the legs. It can cause swelling and pain in the leg, but often occurs without giving any symptoms. A DVT may well settle completely, as the thrombosis is dissolved by natural processes. If a DVT extends up the deep veins, two things can sometimes happen: 1. The thrombosis can become dislodged from the vein, and carried through the main veins and heart to lodge in the lungs. This is called a pulmonary embolism. Small pulmonary emboli may cause chest pain, and sometimes coughing up of blood. Multiple or larger pulmonary emboli may cause breathlessness. A large pulmonary embolus which blocks the main blood vessels to the lungs will be fatal. 2. The thrombosis can cause chronic blocka
