What Are Varicose Veins?

Varicose veins are part of a group of venous disorders that affect the legs. It is a very common condition resulting from decreased blood flow from the leg veins up to the heart, with pooling of blood in the veins.

In people who develop varicose veins, one-way valves in their leg veins become weak and don't close properly, allowing blood to flow backward, a condition called reflux. Veins that have lost their valve effectiveness become elongated, rope-like, bulged, and thickened because they are congested with blood.

When these enlarged veins are smaller, red, blue, or purple veins on the surface of the skin, they are called spider veins. When the veins become larger and are distended, they are called varicose veins.

These enlarged, swollen vessels are a direct result of increased pressure from reflux. A common cause of varicose veins in the legs is reflux on the thigh vein called the greater saphenous vein.