A deep vein thrombosis (thrawm-BOH-sihs), or DVT (D-V-T), is a blood clot that most often occurs in the deep veins of the calf or leg. The major factors that contribute to clot formation are sluggish blood flow, inflammation of the vein wall, and an increased tendency for blood to coagulate, or thicken. Deep vein clots may also form as a result of trauma or surgery. If untreated, DVTs can lead to serious problems, including leg pain and swelling, varicose veins, and ulcers that won't heal. Another danger is that the clot can break loose and lodge in the pulmonary (PULL-moh-nair-ee) arteries of the lung. Known as a “pulmonary embolism,” a clot in this location can be deadly. DVTs may not cause symptoms until the blockage of blood flow is extreme. Signs like pain, sudden swelling of the leg, unusually warm skin, engorged veins near the surface, or a reddish-blue tint to the area may signal a clot and should be investigated by a doctor immediately. Blood thinners can keep a DVT from enlarging and stop new clots from forming. Elevation of the leg and support stockings are also used to treat the condition. The body will usually dissolve most of the clot on its own, but if not, surgery may be required.