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Veins carry blood back to the heart from the tissues. Blood flowing in the veins is under lower pressure and moves more slowly than blood flowing in the arteries. Blood is therefore more likely to clot in the veins, thus blocking the flow through the veins.
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.
