Deep vein thrombosis (DVT) occurs when a blood clot (thrombus) forms in one or more of the deep veins in your body, usually in your legs. Deep vein thrombosis can cause leg pain or swelling, but may occur without any symptoms. It is a very serious condition that can cause permanent damage to the leg, known as post-thrombotic syndrome, or a life-threatening pulmonary embolism. In the United States alone, 600,000 new cases are diagnosed each year.
The deep veins that lie near the center of the leg are surrounded by powerful muscles that contract and force deoxygenated blood back to the lungs and heart. Valves are one-way and prevent the back-flow of blood between the contractions. (Blood is squeezed up the leg against gravity and the valves prevent it from flowing back to our feet.) When the circulation of the blood slows down due to illness, injury or inactivity, blood can accumulate or “pool” which provides an ideal setting for clot formation.