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Deep Vein Thrombosis (Blood Clot in the Leg, DVT)

Deep vein thrombosis (DVT) is a blood clot in one of the major deep veins, usually of the lower legs, thighs, or pelvis. A clot blocks blood circulation through these veins, which carries blood from the lower body back to the heart. The blockage can cause pain, swelling, or warmth in the leg. Blood clots in the veins can cause inflammation called thrombophlebitis. If the clot breaks loose and travels through the bloodstream, it can block a blood vessel in the lungs. Called pulmonary embolism, this can lead to severe trouble breathing and even death.

In the U.S., between 300,000 and 600,000 people per year get deep vein thrombosis. About 100,000 people die each year from pulmonary embolism.

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Deep Vein Thrombosis Causes

Three things can cause a clot to form inside a blood vessel:

  1. Damage to the inside of a blood vessel
  2. Changes in normal blood flow
  3. Hypercoagulability, a state in which the blood is more likely than usual to clot

Anything that contributes to one or more of these three things can cause deep vein thrombosis. The common risk factors are:

  • Sitting for a long time, such as during a long plane or car ride
  • Long bed rest or immobility, such as after an injury or while ill (for instance, after a stroke)
  • Recent surgery, particularly orthopedic, gynecologic, or heart surgery
  • Recent injury to the lower body, such as fractures of the bones of the hip, thigh, or lower leg
  • Obesity
  • Heart attack or heart failure
  • Recent childbirth
  • Being at very high altitude, greater than 14,000 feet
  • Estrogen replacement therapy or birth control pills
  • Cancer
  • Rare, inherited blood-clotting problems
  • Disseminated intravascular coagulation (DIC), a condition in which blood clotting occurs inappropriately, usually caused by overwhelming infection or organ failure
  • Certain heart or respiratory conditions
  • Advanced age

If a person has one deep vein thrombosis, they are more likely to have a second deep vein thrombosis.

Deep Vein Thrombosis Symptoms

Symptoms happen in the leg when a clot blocks blood flow and causes inflammation. Symptoms may include the following:

  • Swelling
  • Pain
  • Redness
  • Warmth to the touch
  • Worsening leg pain when bending the ankle up towards the shin
  • Leg cramps, especially at night
  • Bluish or whitish skin

About 50% of people with deep vein thrombosis do not have symptoms.

When to Seek Medical Care

Call a doctor immediately if you think you have DVT. Although a deep vein thrombosis may get better on its own, it could also lead to a life-threatening pulmonary embolism. The doctor may tell you to go immediately to a hospital emergency room.

If someone has leg pain or swelling with any risk factors for DVT, go to an emergency room immediately.

Call 911 if you or someone you know begins having chest pain, shortness of breath, difficulty breathing, fainting, or any other symptoms that concern you.

WebMD Medical Reference from eMedicineHealth

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