What are Varicose Veins? - 2

Since the weight of the blood is so heavy, the valves are able to hold back the downward flow of blood for only a limited time. Then the vein wall gradually starts to expand. The valves no longer have a nice, tight fit, and blood starts to move down the leg.

As more valves become damaged, more blood is allowed to pool in the vein, and it starts to become visible to the human eye. This is what we call a "varicose vein."

 There is evidence that a weakness of these important valves may be inherited in some people and the valves may also be stretched and caused to leak by obesity and pregnancy. It is unlikely that prolonged standing actually causes varicose veins, although people who spend a great deal of time on their feet are certainly more likely to notice their veins and any symptoms from them.