Deep vein thrombosis (DVT) is a blood clot (also called a thrombus) that forms in a vein deep in the body. Most deep vein clots occur in the lower leg or thigh but can also occur in other parts of the body. This clot may interfere with circulation and it may break off and travel through the blood stream and lodge in the lungs, causing severe damage to that organ. If the clot lodges in the lung, it is called pulmonary embolism. This is a very serious condition that can cause death. Symptoms of pulmonary embolism include chest pain when taking a deep breath, rapid pulse, fainting, shortness of breath and coughing up of blood. Blood clots that remain lodged in the leg can result in pain and swelling.