Deep Venous Thrombosis (DVT)
Deep Venous Thrombosis (DVT) is the formation of a clot ('thrombus') in a vein deep in the body, usually in the lower leg, thigh, or pelvis. Blood clots may form in the blood vessels when the blood does not flow properly, as occurs in people with chronic venous insufficiency.
If the veins are blocked with a blood clot, two problems can occur. If the clot blocks the blood flow back to the heart, the leg can begin to swell, ache and throb. Even more seriously, the clot in the leg vein may break away and travel to the heart and lungs, where it can cause significant damage or death. DVT can be life threatening if a blood clot travels from the leg veins to the heart or lungs (called a pulmonary embolus). Affecting approximately 300,000 people each year in the U.S., pulmonary emboli cause more deaths than breast cancer, AIDS, and accidents combined.
Risk factors for developing blood clots include long air or auto travel, surgery, advancing age, pregnancy, and more (see Risk Factors for DVT, below). In addition to the risk factors associated with venous disease and DVT in particular, abnormal clotting may occur in people with inherited clotting disorders called thrombophilias. These can easily be diagnosed with simple blood tests, but a high index of suspicion is usually needed before performing such tests. If you have had a blood clot already for no apparent reason then you probably should be investigated for having thrombophila. A family history of blood clots in veins, early heart attack in parents or siblings (under age 50) or an early stroke are also reasons to investigate the possibility of an inherited clotting disorder.