Cutting into the eardrum is a procedure done when there is fluid or pus causing the eardrum to bulge. An incision allows this fluid to drain out. If the eardrum were to rupture on its own, the result could be a round hole that might lead to permanent perforation. However, a carefully made surgical incision can heal and close up after the fluid has drained. This procedure is also known as paracentesis of the eardrum.