Deep venous thrombosis (DVT) refers to a blood clot embedded in one of the major deep veins of the lower legs, thighs, or pelvis. A clot blocks blood circulation through these veins, which carry blood from the lower body back to the heart. The blockage can cause pain, swelling, or warmth in the affected leg.
Blood clots in the veins can cause inflammation (irritation) called thrombophlebitis. The most worrisome complications of DVT occur when a clot breaks loose (or embolizes) and travels through the bloodstream and causes blockage of blood vessels (pulmonary arteries) in the lung. This can lead to severe difficulty in breathing and even death, depending on the degree of blockage.
In the United States, about 2 million people per year develop DVT. Most of them are aged 40 years or older. Statistics reveal that at least 200,000 patients die each year from blood clots in their lung.