Sclerotherapy is used for slightly larger spider veins and small varicose veins. Through tiny injections, a painless solution is introduced into the inside of the damaged vein causing it to collapse. Sclerotherapy is performed by the doctor in 30 minute sessions. Fifty to seventy veins can be treated in one session, and compression stockings must be worn for at least 1 week after treatment. After allowing 3-6 weeks for the treated veins to heal, additional treatment on select areas may be needed. For larger varicose veins, endovenous laser (EVLT), ultrasound guided injections or vein microsurgery is necessary. The ultrasound allows the doctor to see larger veins beneath the skin, and place the sclerosing solution in the precise location for maximum effectiveness.