Varicose veins are swollen, twisted, and sometimes painful veins that have filled with an abnormal collection of blood.

See also:

• Varicose vein stripping
• Venous insufficiency

In normal veins, valves in the vein keep blood moving forward toward the heart. With varicose veins, the valves do not function properly, allowing blood to remain in the vein. Pooling of blood in a vein causes it to enlarge.

This process usually occurs in the veins of the legs, although it may occur elsewhere. Varicose veins are common, affecting mostly women.

Causes include:

• Defective valves from birth (congenitally defective valves)
• Thrombophlebitis
• Pregnancy

Standing for a long time and having increased pressure in the abdomen may make you more likely to develop varicose veins, or may make the condition worse.

Primary varicose veins occur because of congenitally defective valves, or without a known cause. Secondary varicose veins occur because of another condition, such as when a pregnant woman develops varicose veins.