Incision and drainage is a minor surgical procedure to release pus or pressure built up under the skin, such as from an abscess, boil, or infected paranasal sinus. It is performed by treating the area with an antiseptic, such as iodine-based solution, and then making a small incision to puncture the skin using a sterile instrument such as a sharp needle, a pointed scalpel or a lancet. This allows the pus fluid to escape by draining out through the incision.