Although this procedure has been used in Europe for more than 50 years, it has only become popular in the United States during the past decade. The introduction of sclerosing agents that are mild enough to be used in small veins has made sclerotherapy predictable and relatively painless. Spider veins known in the medical world as telangiectasias or sunburst varicosities are small, thin veins that lie close to the surface of the skin. Although these super-fine veins are connected with the larger venous system, they are not an essential part of it. 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.
Spider veins usually take on one of three basic patterns.
Linear spider veins are commonly seen on the inner knee, whereas the arborizing pattern often appears on the outer thigh in a sunburst or cartwheel distribution. Varicose veins differ from spider veins in a number of ways. Varicose veins are larger usually more than a quarter-inch in diameter, darker in color and tend to bulge. Varicose veins are also more likely to cause pain and be related to more serious vein disorders. For some patients, sclerotherapy can be used to treat varicose veins.