Deep vein thrombosis (DVT) is a blood clot in a vein deep in the body. Veins are blood vessels with valves that help prevent backward blood flow. Blood is pushed through the veins in legs and arms when muscles contract.

Deposits of red blood cells and clotting elements in the blood can build up in a vein. This build up leads to a blood clot. Clots usually occur in the legs, but can occur in other locations. As the clot grows, it blocks blood flow in the vein.

Deep Vein Thrombosis
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Several factors contribute to clot formation, including:

  • Slow blood flow, often due to lying or sitting still for a long period of time
  • Pooling of blood in a vein, often due to:
    • Immobility
    • Medical conditions
    • Damage to valves in a vein or pressure on the valves, such as during pregnancy
  • Injury to a blood vessel
  • Clotting problems, which can occur due to aging or disease
  • Catheters placed in a vein