Spider veins are small, dilated veins that form web-like or sunburst patterns on the legs and face.

A number of factors contribute to the development of spider veins, including heredity, pregnancy and other events that cause hormonal shifts, weight-gain, occupations or activities that require prolonged sitting or standing and the use of certain medications.

Vein therapy, often performed on an outpatient basis, can be effective in 50 to 90 percent of cases. Treatments include sclerotherapy, in which blood vessels are injected with a solution that causes them to shrink and disappear. Several veins may be treated during one visit, and repeated treatments may often be needed, depending on the size of the blood vessels involved.