Deep vein thrombosis, a blood clot in a large vein usually in a leg, strikes around 2 million Americans each year. As common as it is, it should not be dismissed as harmless. Though it is usually not life-threatening, the clot can travel to the lungs, causing a pulmonary embolism, or the brain, causing a stroke, and those conditions can be fatal. Deep vein thrombosis is thus responsible for approximately 200,000 deaths each year.
The direct cause of the condition is restricted mobility, and so it is generally associated with airplanes—sitting for a long time in cramped circumstances, not walking around or even changing position. However, deep vein thrombosis is also common after long hospital stays, certain types of surgery including knee and hip replacement, some kinds of cancer, and some kinds of cancer treatment. In addition, there are blood disorders that can cause clotting and make people prone to thrombosis, and heart disease is also a risk factor. Some of these diseases are hereditary, meaning people with a family history of deep vein thrombosis or other clotting disorders need to be particularly on alert.
In addition to walking around when possible, there are steps you can take to lower the risk of deep vein thrombosis. Vitamin K contributes to clotting, and it’s found in green leafy vegetables, liver and foie gras, and certain cooking oils. People who are unavoidably going to be still for a while—for instance, after surgery—can get compression stockings to help prevent clotting in the legs. In some cases, people who are especially vulnerable to clots may be prescribed medications called anti-coagulants, or blood thinners, to prevent them.
Left untreated, thrombosis can lead to pulmonary embolism or stroke, or to a condition called postphlebitic syndrome. The pain and swelling in the legs and discolored skin that characterize postphlebitic syndrome may not occur for months or even years after the thrombosis occurs. Treatments include anti-coagulants and medications that break up clots. In some cases a wire filter can be put in a wide blood vessel to break up clots before they reach the slightly narrower veins in the legs.