While genetic predisposition appears to be important, nobody is exactly sure why spider veins develop. Pregnancy, estrogen therapy, prolonged standing, and trauma are known to make spider veins worse.
Sclerotherapy is a technique for injecting a small amount of a sclerosing solution into unwanted vessels on the legs. The solution irritates and damages the inner lining of the blood vessels without damaging the surrounding tissue. This produces an imperceptible scar within the blood vessel, which eventually contracts and disappears under the skin. As the procedure is directed at small surface vessels, it does not affect the underlying circulation.
For Sclerotherapy to work, several injections may be required to eliminate a specific vessel. The procedure also involves tolerating a minimal amount of pain associated with the fine needle stick which is required to inject the sclerosing solution.
Each individual vessel that is treated with Sclerotherapy requires one to four treatments to completely disappear. The vessels will disappear two to three months after being treated. Recurrences may occur one to five years following treatment. Treatment does not prevent new spider veins from forming.