The related blood clot problems—deep vein thrombosis (DVT) and pulmonary embolism (PE)—are known as ‘venous thromboembolism’ (VTE for short) and are one of the most common causes of hospital deaths that can be prevented in the UK.
DVT refers to a blood clot that forms in one of the major deep veins of the lower legs or thighs, or sometimes in the pelvis. A clot blocks blood circulation through these veins, which carry blood from the lower body back to the heart. The blockage can be painful and cause swelling or warmth in the affected leg. Blood clots in veins can also cause inflammation called thrombophlebitis.
A serious complication of DVT that can be life threatening occurs when a clot breaks loose (or embolises) and travels through the bloodstream, causing blockage of blood vessels (pulmonary arteries) in the lung, known as PE. If this happens, a person can have difficulty in breathing, experience chest pain, and some will cough up blood-stained phlegm.
The figure shows how a DVT embolises from the left leg and travels through the bloodstream and blocks a pulmonary artery in the left lung.