This is a medical procedure to treat spider veins and small varicose veins on the legs.  A solution (typically a concentrated salt water) in injected into the vein and causes irritation to the lining of the vessel.  This causes the walls of the vessel to stick together and permanently close the vessel off.  This in turn, shunts blood flow back into normal, healthier circulation.  Sclerotherapy is considered the gold standard for treatment of spider veins over other treatments, including laser.  Usually requiring at least two treatments and patients are encouraged to wear compression stockings for two weeks following treatment for best results.