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 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 (PE). This is a very serious condition that can cause death. DVT and PE are collectively called venous thromboembolism (VTE) and are predisposed by the same risk factors.