Sclerotherapy is injecting a solution into a diseased vein to sclerose or seal the vein closed. The solution causes irritation of the vein wall which makes it sticky. Over time, the veins seal shut and are reabsorbed by the body. The injections are done through very small needles and are relatively painless. Different concentrations of the sclerosing solution are used depending on the size of the vein being treated.

Ultrasound guided sclerotherapy, as the name implies, is injecting a sclerosing solution into a vein using ultrasound to direct the injection. This is done to treat veins which are not visible from the skin surface. It is helpful to eliminate veins which are feeding spider veins, to treat incompetent perforater veins which are contributing to chronic venous insufficiency/venous ulcers, or to seal off the origin of a varicose vein.