A deep venous thrombosis or DVT is a vascular disorder resulting from the formation of a blood clot (thrombus) inside a deep vein of the upper or lower extremities. Most frequently, a DVT will occur in the leg or thigh when a blood clot either partially or completely blocks the flow of blood in the vein. Patient symptoms can include pain, swelling, and discoloration. Left untreated, a deep vein thrombosis (DVT) can break off and travel in the circulation, getting trapped in the lung, where it blocks the oxygen supply, causing heart failure. This is known as a pulmonary embolism or PE, which can be fatal. When a DVT is suspected an immediate evaluation and diagnosis (typically with and ultrasound) needs to be established in order to initiate appropriate treatment.