Pulmonary embolism is when one or more pulmonary arteries in your lungs become blocked. In most cases, pulmonary embolism is caused by blood clots that travel to the lungs from the legs or rarely other parts of the body (deep vein thrombosis, or DVT).
Because pulmonary embolism almost always occurs in conjunction with deep vein thrombosis, some doctors refer to the two conditions together as venous thromboembolism (VTE).
Although anyone can develop deep vein thrombosis and pulmonary embolism, factors such as immobility, cancer and surgery increase your risk.
Pulmonary embolism can be life-threatening, but prompt treatment can greatly reduce the risk of death. Taking measures to prevent blood clots in your legs also can help protect you against pulmonary embolism.