The modifier 50 is defined as a bilateral procedure performed on both sides of the body.
Services will be rejected as unprocessable when the procedure code reported is inconsistent with the modifier used.
Claims for bilateral surgical procedures should be billed on a single claim detail line with the appropriate procedure code and modifier 50 and one (1) unit of service (UOS).
If more than one bilateral procedure was performed the number of units should be adjusted to reflect the number of bilateral procedures that are performed.
Procedure code 19303 (Mastectomy, simple, complete) is performed bilaterally.
Correct coding
Date of service |
Procedure code |
Modifier |
Units |
6/1/2024 |
19303 |
50 |
1 |
Incorrect coding
Date of service |
Procedure code |
Modifier |
Units |
6/1/2024 |
19303 |
LT |
1 |
6/1/2024 |
19303 |
RT |
1 |
To report surgical procedures identified by their terminology as "bilateral".
To report surgical procedures identified by their terminology as "unilateral or bilateral," regardless of whether the procedure is performed bilaterally or not.
Do not append to procedures for midline organs such as the bladder, uterus, esophagus, or nasal septum.
Inappropriate to report when performed on different areas of same side of body.
Modifier 50 cannot be appended when bilateral indicators are 0, 2, 3 or 9. (*)
Modifier 50 cannot be appended to an add on code.
The terminology for procedure code 27158 (osteotomy, pelvis, bilateral) indicates the procedure is performed bilaterally. Therefore, it’s not appropriate to report modifier 50 with this procedure code.
“0" indicates a unilateral code; modifier 50 is not billable.
"1" indicates modifier 50 can be appropriate.
"2" indicates a bilateral code; modifier 50 is not billable.
"3" indicates primary radiology codes; modifier 50 is not billable.
"9" indicates that the concept does not apply.
When reporting bilateral surgical procedures that have an MUE adjudication indicator (MAI) of "2" or "3", bill with modifier 50 and one unit of service.
ASC specialty providers don't report modifier 50.
When more than one surgical procedure is performed in the same operative session, multiple surgery rules apply.
Medicare will allow 100% of the highest paying surgical procedure on the claim plus 50% for the other ASC-covered surgical procedures furnished in the same session.
Bilateral procedures should be reported:
Single unit on two separate lines or a single unit on one line with "2" in the unit field, for both procedures to be paid correctly.
Multiple procedure reduction of 50% will apply to all bilateral procedures subject to multiple procedure discounting.
Multiple surgery pricing applies to bilateral services (modifier 50) performed on the same day with other procedures.