Spider veins are smaller, but often more colorful, than varicose veins. They are fine clusters of veins which are blue or red but are not raised. While varicose veins are usually found on your legs, spider veins may also be found on other areas of your body including your arms and face. They are small dilated blood vessels near the surface of the skin usually between 0.5 and 1 millimeter in diameter. They can develop anywhere on the body but are often seen on legs, specifically on the thigh, below the knee joint, and around the ankles. Spider veins are often related to the presence of venous hypertension within underlying varicose veins. Abnormal blood flow in reticular feeder veins can lead to the development of surface spider veins.
Spider veins are more prominent in women than men- almost four to one. Research suggests that this is due to increased hormone levels and blood volume during pregnancy which creates too much pressure against the walls of the veins. This condition, called venous distention, may lead to damaged vein valves thus allowing back flow and pooling of blood. Spider veins may occur at any age, but frequently first occur between 18 and 35 years, peaking between ages 50 and 60.