Why Do Veins Have Valves?

Veins are vessels that transport blood without oxygen and nutrients back to the heart. In healthy leg veins, one-way valves allow blood to move only in one direction: towards the heart.

When valves in veins fail to work properly, the valves do not close, and blood is allowed to flow backward in the wrong direction. Over time, the blood can pool within your legs, which can consequently cause more vein valves to malfunction.
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