For both the modifier OP report must be submitted, according Medicare: The Medical Review department has determined that many claims are being denied for lack of information regarding modifiers 52 and 53. Modifier 52 – Reduced Services Modifier 53 – Discontinued Procedure If modifier 52 is used and the procedure is surgical, an operative report must be submitted along with the claim and a separate concise statement indicating how the service differs from the usual. If the reduced procedure is non-surgical, a statement or report must be submitted describing how the service performed differs from the usual. If modifier 53 is used for a surgical procedure, an operative report is required. If the procedure is not surgical, a statement or report of how the procedure performed differed from the usual must be submitted with the claim.