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Blood clot formation in the veins is called venous thrombosis. Venous thrombosis most commonly forms in the veins of the legs. Risk factors for venous thrombosis include prolonged bed rest or immobility, as can be necessary after surgery, cancer, and estrogen therapy.
Review Date 4/1/2025
Updated by: Linda J. Vorvick, MD, Clinical Professor Emeritus, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.