ARE YOU AT RISK FOR DVT?

Deep venous thrombosis (or DVT) is a condition in which a blood clot forms inside a vein, most often one of the deep veins of the legs or the pelvis. This clot (or thrombus) can block the circulation of blood through the vein, causing leg swelling, warmth, or pain. Part of the clot can break off (or embolize) and travel through the venous system. This is called an embolism. If the clot lodges in the blood vessels of the lungs, it is called a pulmonary embolism or PE. This can be a very serious complication, leading to severe breathing difficulties and even death. About 600,000 to two million people in the U.S. per year develop DVT and approximately 10 percent of these die each year from pulmonary embolism.

Typically, blood clots are caused by one of three conditions: damage to the inside of the blood vessel, changes in normal blood flow including turbulence or blockage, and rare conditions leading to an increased tendency of the blood to clot. The most common risk factors are prolonged sitting, as in a long car or airplane trip, prolonged bed rest or immobility, cigarette smoking, recent surgery, fractures of the leg or hip bones, obesity, age over 50, and rare inherited changes in blood clotting factors (hypercoagulability). Women have additional risk factors, including recent childbirth and use of estrogen replacement or birth control pills. In addition, medical conditions such as a history of heart attack, heart failure, or cancer also increase risk of DVT.

Your doctor will suspect DVT if you complain of leg swelling, warmth, tenderness, and possibly discoloration of the skin. Usually, only one leg is involved, and the symptoms may come on gradually over a few days. The most common test used to diagnose DVT is an ultrasound of the veins of the affected leg. In this test, an ultrasound wand is moved back and forth on the skin over the leg veins and sends images to a machine that displays pictures of the blood flow in the leg.

If you have DVT, the primary goal of treatment is to prevent a life-threatening PE, most commonly by using anticoagulants or blood thinners. These medications will not dissolve the existing clot, but they will keep the clot from getting bigger and prevent new clots from forming.

Heparin is an intravenous medication which must be administered in the hospital and must be monitored with blood tests every few hours. Low-molecular-weight heparins (for example, Lovenox) are newer medications which are delivered via shots below the skin surface and can be given at home.

The most common blood thinner is Coumadin, which is a pill taken daily. Taking Coumadin can be a challenge, because it interacts with many medications and requires frequent blood tests to ensure that your blood is neither too thin nor too thick. Coumadin takes several days to have the right effect, so doctors will often order one of the other medications to thin the blood until the Coumadin is at a therapeutic level. Treatment with anticoagulants is usually continued for at least six months.

Some people are not good candidates for a blood thinner. This includes people who would have a high risk of bleeding if their blood was too thin, for example, people who are unsteady and likely to fall or people who have just had surgery. These people might be good candidates for a filter, which is a device placed into the large vein (inferior vena cava) that connects the legs to the heart. This filter does not stop new clots from forming but traps them and prevents them from passing from the legs into the lungs.

Although DVTs often resolve on their own, if you suspect that you may have a DVT, you should contact your doctor for urgent evaluation because of the potentially life-threatening consequences of a pulmonary embolism.

Dr. McMahon, a graduate of Yale University and the University of Pittsburgh School of Medicine, is board certified in Internal Medicine. She is a member of the American College of Physicians and the Allegheny County and Pennsylvania Medical Societies. She is in solo practice in the North Hills of Pittsburgh.