A DVT is a blood clot in a vein, usually in the lower leg. If a clot in a vein breaks loose, it can travel to your lungs and block a blood vessel. This can cause breathing problems or even death.

Am I at risk for DVT?

If you're not very active, you're at risk for DVT. People who aren't active, those who are paralyzed, and anyone confined to bed for any reason are at increased risk for DVT. Sitting for long periods, as you would on a long airplane trip, raises your risk of DVT too.

Dehydration increases the risk because it makes the blood thicker and slows circulation. You can become dehydrated if you don't drink enough fluids or if you take medicine that makes you lose fluids, such as diuretics (water pills). Being dehydrated and inactive increases your risk even more.

Other risk factors for DVT include recent surgery, a cancer diagnosis, older age, pregnancy, and obesity.

How will I know if I have a DVT?

If you develop a DVT, you'll probably have pain or tenderness and swelling in one of your legs. The area may look purple or red and feel warm to the touch, and the vein may feel hard. Call your healthcare provider if you have any of these symptoms.

Some people don't have any symptoms until the clot moves from the leg to the lungs. A clot in the lungs generally causes chest pain and shortness of breath. This is an emergency. If you have these symptoms, call 911 immediately.

Your healthcare provider can use several tests to look for DVT. First, you'll probably undergo a painless ultrasound test to look for a clot in your leg. If the clot doesn't show on ultrasound, you may undergo a special X-ray test at the hospital that involves injecting a liquid into your veins and taking pictures of your veins to look for a clot.

How is a DVT treated?

Most DVTs can be treated with blood-thinning medicines given as pills, shots, or I.V. infusions. Before you start blood-thinner treatment, your healthcare provider will draw blood for tests, including one that measures the time it takes your blood to clot. These values will be followed closely while you undergo treatment to make sure your blood isn't getting too thin.

Other measures to treat DVT include warm, moist compresses and special stockings. Your healthcare provider may suggest elevating your leg for short periods to help reduce swelling.

Most people with DVTs take blood thinners for at least 3 months, but some need them longer. If you need therapy with a blood thinner such as Coumadin (warfarin), your healthcare provider will explain when to take it in relation to other medicines, vitamins, supplements, and foods. Many things can interfere with how well Coumadin works, so take the medicine as directed and get your blood checked regularly as directed by your healthcare provider.

How can I prevent a DVT?

Here are some steps you can take to reduce your risk of problems:

* Avoid long periods of inactivity and don't cross your legs. If you must sit for a long time when flying, get up and walk around every hour or so.

* Stay active. Get regular moderate exercise, such as taking walks.

* Drink plenty of noncaffeinated, nonalcoholic fluids each day so you don't get dehydrated.

* Wear special support stockings if your healthcare provider advises.

* Don't smoke. If you do, contact your healthcare provider for help with stopping.

* If you're too heavy, lose weight. Your healthcare provider can guide you to a program that's right for you.