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Deep Vein Thrombosis

Deep vein thrombosis (DVT) is a blood clot or thrombus in a deep vein. These blood clots are most common in the leg. But they may occur in the arm or other part of the body. Part of a clot, called an embolus, can break off and travel to the lungs. This is a pulmonary embolus (PE). This can cut off blood flow to all or part of the lung. PE is an emergency and may cause death.

Healthcare providers use the term venous thromboembolism (VTE) to describe these 2 conditions, DVT and PE. They use the term VTE because the 2 conditions are very closely related. And because their prevention and treatment are also closely related.

What causes deep vein thrombosis?

The deep veins of the legs are located in the muscles. These help carry blood from the legs to the heart. When leg muscles contract and relax, blood is squeezed through the veins back to the heart. One-way valves inside the veins help keep the blood moving in the right direction. When blood moves too slowly or not at all, it can collect (pool) in the veins. This makes a clot more likely to form.

Who is at risk for deep vein thrombosis?

Anyone can develop a blood clot. But certain factors may raise your risk for one. Anything that slows blood flow, injures the lining of a vein, or increases blood clotting can make you more likely to have DVT. You are at risk for DVT if you:

  • Are overweight or obese
  • Have a blood-clotting disorder
  • Are older than age 60
  • Had surgery
  • Have spent a long period of time not moving, such as staying in the hospital or traveling on a long trip
  • Take birth control pills or hormone replacement therapy
  • Are paralyzed
  • Are pregnant
  • Smoke
  • Have a central venous catheter (for example, in a large vein in the chest)

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