What Causes Deep Vein Thrombosis in the Leg?

Last Editorial Review: 10/3/2017

Ask the experts

What causes deep vein thrombosis in the leg?

Doctor's response

Blood is meant to flow. If it becomes stagnant, there is a potential for it to clot. The blood in veins constantly forms microscopic clots that are routinely broken down by the body. If the balance of clot formation and clot breakdown is altered, significant clotting may occur. A thrombus can form if one or a combination of the following situations.


  • Prolonged travel and sitting, such as long airplane flights ("economy class syndrome"), car, or train travel
  • Hospitalization
  • Surgery
  • Trauma to the lower leg with or without surgery or casting
  • Pregnancy, including 6-8 weeks post-partum after delivery of the baby
  • Obesity

Coagulation of the blood faster than usual (hypercoaguability)

Read our full medical article for more information about deep vein thrombosis symptoms, causes, treatment, and prognosis.

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