Bilateral indicators

The Medicare physician fee schedule status indicators for bilateral services should be used to determine if the procedure is allowed to be performed bilaterally. 

Bilateral indicator "0"

Bilateral adjustment is inappropriate for codes in this category because of (a) physiology or anatomy or (b) because the code descriptor specifically states it is a unilateral procedure and there is an existing code for the bilateral procedure.

• Services may be unilateral, or another procedure code exists for services performed bilaterally.
• Procedure code should not be reported with a 50, RT or LT modifier.
• If reported bilaterally only one unit will be considered for payment.

Bilateral indicator "1"

Bilateral procedures must be reported with 1 unit of service and the modifier 50. Modifier 50 identifies the service as being performed on both sides of the body. Do not report anatomical modifiers in addition to modifier 50. 

• If more than one bilateral procedure was performed, report the services on one line, the number of units should be adjusted to reflect the number of bilateral procedures that are performed.
• It is recommended that anatomical modifiers only be included when the service is performed unilaterally to show the additional services are not duplicates.

Bilateral procedure reduction applies and payment for both sides is based on the lower of the actual billed amount or 150% of the fee schedule amount for one unit.

Example 1:

An arthrocentesis (CPT code 20600) was performed on the right and left index fingers.

Correct coding

Incorrect coding 1

Incorrect coding 2

Example 2:

An arthrocentesis (CPT code 20600) was performed on the right and left index fingers and the right and left thumbs.

Correct coding

Incorrect coding 1

Example 3:

An arthrocentesis (CPT code 20600) was performed on the right and left index fingers and the right thumb.

Correct coding 1

Incorrect coding 1

Note: Ambulatory surgical centers cannot append modifier 50 on bilateral surgery claims. Bilateral procedures must be reported on two separate lines appending the appropriate RT or LT modifier.

Bilateral indicator "2"

• Modifiers 50, LT or RT are not allowed because the procedure is priced to include a bilateral service.
• Code description may include terms like “bilateral” or “unilateral or bilateral”.
• Bilateral procedure reduction does not apply because services are already priced as a bilateral service. 

Bilateral indicator "3"

• These codes are not considered bilateral therefore, modifiers 50, LT and RT aren't billable.
• Bilateral procedure reduction does not apply, and services are processed based on the number of services performed.
• To ensure proper coding and billing of units of service, review the medically unlikely edits 

References 

• CMS IOM Publication 100-04 Medicare Claims Processing Manual, Chapter 12, section 40.7
• Modifier 50 fact sheet
• Global Surgery MLN Fact Sheet
• Global surgery & related services
• Medicare physician fee schedule payment policy indicators
• National Correct Coding Manual, Chapter 1 General Coding Policies