2007 ICD-9-CM Procedure 20.4 Mastoidectomy 20.4 is a non-specific code that should not be used to specify a procedure View the full Volume 3 20.* hierarchy Code also any: skin graft (18.79) tympanoplasty (19.4-19.55) 20.4 excludes: that with implantation of cochlear prosthetic device (20.96-20.98)