Varices are large, dilated veins that develop in the esophagus when there is elevated pressure in the portal vein, the large vein that enters the liver. This elevated pressure can occur under several circumstances including severe liver disease and thrombosis (clotting) of the portal vein. Sometimes these varices can bleed or be at high risk of bleeding. These can be controlled either by banding (see above) or sclerosing the varices. Sclerotherapy is performed by injecting a medication into the varix that causes it to scar. If the varix is scarred, it cannot bleed. This is done while your child is asleep under anesthesia. A fiber optic tube (endoscope) is passed through the mouth and into the esophagus. A sclerotherapy needle is passed through the endoscope. Once a varix is identified, the needle is advanced into the vein and the medication injected. Several different varices can be injected at the same session. It often requires several sessions, each scheduled several weeks apart, to take care of all the varices.