Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link
Valves in Varicose Veins
Valves in Varicose Veins

In a normal vein, the cusps of the valves close to prevent backward flow of blood. In a varicose vein, the cusps cannot close because the vein is abnormally widened. Consequently, blood can flow in the wrong direction.

In these topics
Varicose Veins