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Deep Vein Thrombosis Health Center

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Danger! Deep Vein Thrombosis

Could you have a life-threatening blood clot?

What Is Deep Vein Thrombosis?

DVT is caused by a blood clot -- or thrombus -- that develops in one of the larger veins in your body, usually in the lower legs. Occasionally, it can develop elsewhere, like in the arms, says Merli. The clot can partially or completely block the circulation in the area around it.

Deep vein thrombosis can cause problems in itself. But its greatest risk is that part of the blood clot will break away and travel through the bloodstream.

The veins carry the clot up the legs, to the heart, and into the lungs. If the clot lodges in one of the arteries of the lungs, it can prevent oxygen from getting into the blood. This is called a pulmonary embolism. It can be treated in many cases. But if the clot completely blocks the artery, as it did in David Bloom's case, it can cause death.

Who Is at Risk for Deep Vein Thrombosis?

Blood clots can develop for various reasons. They most often occur if your circulation is decreased or slows down in a particular area. When blood stops flowing freely, it becomes stagnant and naturally begins to clot.

"There are three classic factors in developing DVT," says Bruce A. Perler, MD, chief of the division of vascular surgery at Johns Hopkins School of Medicine in Baltimore. They are:

  • Prolonged immobility. If you're in a confined area for long periods of time and can't stretch your legs, your circulation can get worse. This is why deep vein thrombosis is more common in people who are stuck in bed or taking long trips. Because DVT often occurs after long plane flights, it is sometimes called "economy class syndrome."

  • Trauma -- from an accident or surgery. Damage to the tissue can increase the blood's tendency to clot. This can happen after accidents or, more often, after an operation.

  • Genetic predisposition to clotting. Some people -- although many of them don't know it -- have inherited a higher risk of getting deep vein thrombosis. Their blood is more likely to clot than average. After his death, doctors discovered that Bloom had a genetic blood disorder.

Some diseases, health conditions, habits, and treatments can also increase the risks of getting deep vein thrombosis. They include:

  • Obesity
  • Advanced age
  • Smoking
  • Dehydration
  • Pregnancy
  • High blood pressure
  • Cancer
  • Heart disease or stroke
  • Hormone replacement therapy
  • Birth control pills

In many people, the risk factors are compounded. For instance, if you have heart disease, you might not get as much exercise as you once did. You become more sedentary and start gaining weight. Combining heart disease, excess weight, and immobility dramatically raises your risk of deep vein thrombosis.

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