DEAR EMBARASSED: You are not alone. Almost 75 percent of adults are not familiar with DVT -- short for Deep-Vein or Deep Venous Thrombosis.

DVT refers to a blood clot in the legs, specifically in a "deep vein" (a vein that accompanies an artery). A clot (thrombosis), of course, can interfere with normal blood circulation, but a more serious problem occurs when the clot breaks off and travels through the blood stream (embolism) lodging itself in a critical organ such as the brain, lungs, or heart and causing serious or even fatal damage (often in the form of a pulmonary embolism). Although DVT can occur in any age group, it occurs most frequently among adults over age 60.

According to the American Medical Association, more than 600,000 people suffer from DVT in the UNited States every year, of which at leasy 60,000 will die from pulmonary embolisms. The symptoms might include leg pain or tenderness in one leg, swelling, increased warmth in one leg, or even changes in the skin color of one leg. After the clot has formed, these symptoms might not occur right away and might take hours or even days before showing up.

DVT is usually associated with confined or relatively immobile situations such as driving for long distances or sitting at a computer desk for extended periods of time, but it can occur even in a hospital bed. Not surprisngly, DVT has become so associated with cramped airline seats that it is sometimes referred to as "economy class syndrome." It is the relative immobility -- the lack of physical activity -- that apparently precipitates the clotting even in otherwise healthy individuals, although physical conditions such as obesity, smoking, high blood pressure, or even birth control pills may exacerbate the possibility of DVT (source: MedlinePlus Medical Encyclopedia).

The best way to prevent DVT? Exercise. Why? Because physical activity stimulates circulation and prevents the formation of dangerous clots. Other suggestions? Wear loose-fitting clothes, take periodic breaks to stretch and move around when confined or when sitting too long in one place, and stay well hydrated. Compression stockings or support hose may also help.