Deep venous thrombosis

Alternative names:

clot in the legs; DVT; peripheral thrombosis

Definition:

A condition where there is a blood clot in a deep vein (a vein that accompanies an artery).

Causes, incidence, and risk factors:

Deep venous thrombosis (DVT) affects mainly the veins in the lower leg and the thigh. It involves the formation of a clot (thrombus) in the larger veins of the area. This thrombus may interfere with circulation of the area, and it may break off and travel through the blood stream (embolize). The embolus thus created can lodge in the brain, lungs, heart, or other area, causing severe damage to that organ.

Risks include prolonged sitting, bedrest, or immobilization; recent surgery or trauma, especially hip surgery, gynecological surgery, heart surgery, or fractures; childbirth within the last 6 months; obesity; and the use of medications such as estrogen and birth control pills. Risks also include a history of polycythemia vera, malignant tumor, hypercoagulability (changes in the levels of blood clotting factors making the blood more likely to clot), disseminated intravascular coagulation (DIC), and dysfibrinogenia. DVT may be associated with, or may cause, pulmonary embolus.

Deep venous thrombosis occurs in approximately 2 out of 1,000 people. The condition is most commonly seen in adults over age 60.