Post operative period Billing - Modifier usage POST-OPERATIVE PERIOD BILLING Unrelated Procedure or Service or E/M Service by the Same Physician During a Post-operative Period . Two CPT modifiers are used to simplify billing for visits and other procedures that are furnished during the post-operative period of a surgical procedure, but not included in the payment for surgical procedure. These modifiers are: • Modifier “-79” (Unrelated procedure or service by the same physician during a post-operative period). The physician may need to indicate that a procedure or service furnished during a post-operative period was unrelated to the original procedure. A new post-operative period begins when the unrelated procedure is billed. • Modifier “-24” (Unrelated E/M service by the same physician during a post-operative period). The physician may need to indicate that an E/M service was furnished during the post-operative period of an unrelated procedure. An E/M service billed wi...