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 clot may interfere with circulation, and it may break off and travel through the blood stream (embolize). A resulting embolus can lodge in the brain, lungs, heart, or other area, causing severe damage to that organ. Risks include prolonged sitting, bedrest, or immobilization (such as on long plane or car trips), recent surgery or trauma (especially hip, knee or gynecological surgery), fractures, childbirth within the last 6 months and the use of medications such as estrogen and birth control pills. Risks also include a history of polycythemia vera, malignant (cancerous) tumor, and inherited or acquired hypercoagulability (a condition where the blood is more likely to clot). Deep venous thrombosis is most common in adults over age 60 but can occur in any age group.
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