Myringotomy: A surgically placed tiny incision in the eardrum. Any fluid behind the eardrum can then drain and usually thickened secretions can be removed. A small plastic ear tube (a tympanostomy tube) is often inserted into the eardrum to keep the middle ear aerated for a prolonged period of time. These ventilating tubes usually remain in place for 6 months to several years. Eventually, most of these tubes will move out of the eardrum (extrude) and fall into the ear canal.