March is Deep-Vein Thrombosis Awareness Month, which may have gone unnoticed if not for news of tennis star Serena Williams' recovery from a pulmonary embolism she had last week.


In case you're unaware of the connection between deep-vein thrombosis and pulmonary embolism, the former, commonly known as DVT, is a clot formed deep in the veins of the lower leg, thigh or pelvis. The piece of the clot that detaches and travels through the arteries to the lungs is a pulmonary embolism. Once the traveling clot is in the arteries, it can obstruct the flow of blood to the lungs and cause the heart to overwork, possibly becoming fatal.

"It's what we call sudden death - you're feeling good one minute and the next you're dead because so much pressure is put on your heart and it stops," explains Roy L. Silverstein, M.D. of The Cleveland Clinic Foundation.

The Centers for Disease Control reports that of the 200,000 to 400,000 people who have DVT in the United States, 25 percent of those occurrences would develop into pulmonary embolisms.

DVT itself is rarely fatal and easy to identify. An ultrasound examination is an effective and painless method used for detection. Another simple method involves testing your blood which, if producing positive results, would require you to receive a sonogram to confirm the findings. If pulmonary embolism is suspected, your doctor would take a CAT scan of your lungs to see if a clot is present.

Although symptoms associated with DVT are very nonspecific, a few physical signs of its presence include the thigh or calf feeling very tender or if the leg is painfully swollen, Silverstein says.

Conditions such as pregnancy, smoking, taking birth control pills or estrogen-laden medications often put people at risk for developing DVT. It isn't necessarily race or gender specific and there are some hereditary conditions make some people more susceptible than others. Surgical procedures that cause people to be inactive for a longer time period and long airline flights also are contributors.

Silverstein doesn't know Williams or her medical history outside of media reports, but says it's possible that her leg injury, immobility during recovery, wearing a cast and traveling schedule could have played a role in her developing pulmonary embolism. "It's probably not any one thing but a bunch of things happening at the same time," he says.

Silverstein listed three ways DVT could be prevented:

1. Stop Smoking. Silverstein says this is probably one of the most important things because smoking makes the blood more likely to form clots.

2. Stretch legs during long flights. If taking a long airline trip, drink plenty of fluids and walk around the cabin to help get the blood flowing. "Activity is very important," Silverstein says.

3. Be aware. If you wake up and notice one leg is swollen or bigger than the other, contact your doctor. If you were recently released from the hospital, follow the physical rehabilitation regimen that your doctor recommended so you won't develop DVT.

To find out more about DVT, visit the American Society of Hematology at www.hematology.org.