Which modifier is utilized when a service is performed on opposite sides of the body?

The modifier used when a service is performed on opposite sides of the body is modifier 50. This modifier indicates that a procedure was performed bilaterally, meaning that the same procedure was done on both sides of the body. For example, if a surgeon performed a knee arthroscopy on both the left and right knees, modifier 50 would be appended to the procedure code to indicate this bilateral surgery, allowing for appropriate reimbursement for the additional work involved in treating both sides.

Each of the other modifiers listed has different purposes: modifier 51 is used to indicate multiple procedures performed during the same session, modifier 58 is for staged or related procedures that occur during the postoperative period, and modifier 59 is used to denote a distinct procedural service, indicating that a procedure or service was separate from other services provided on the same day. These modifiers serve specific billing and coding functions but do not denote bilateral services as modifier 50 does.