Avoid the Top 10 Modifier Mistakes – Modifier 50

Matching CPT code with an ICD 10 code, would seem to be a very straightforward process but there are always variations/exceptions to everything. Sometimes, there are related services that the physician is performing, global periods to contend with, etc. Modifiers will clarify extenuating circumstances, which should allow for payment when they otherwise may not. That said, the improper use of modifiers can be the cause of claim denials just as not using a modifier can be. When using modifiers, make sure you clearly understand what the modifier entails.

In this, and the following blogs, we identify 10 of the most commonly misused modifiers to help you become more aware of the issues surrounding them. We’ll help you understand why they are problematic and how you can use them correctly.

Modifier 50

Modifier 50 is used to report bilateral procedures that are performed during the same operative session by the same physician in either separate operative areas (e.g. hands, feet, legs, arms, ears), or one (same) operative area (e.g. nose, eyes, breasts).

Different carriers require different reporting of bilateral procedures and offer different reimbursement methodologies. For examples of common carrier preferences, see Table.

Sample Carrier Preferred Format


# of Units

Modifier 50 on one line Line 1: XXXXX-50 1 Unit
Procedure on two lines
Modifier 50 appended to the second procedure
Line 1: XXXXX
Line 2: XXXXX-50
1 Unit
1 Unit
LT/RT modifiers
Appended to the procedure on one line
Billed as 2 units
Line 1: XXXXX-LT, RT 2 Units
Procedure listed twice
RT/LT modifiers appended
Modifier 59 on the second procedure
Line 1: XXXXX-LT
Line 2: XXXXX-59, RT
1 Unit
1 Unit

When using Modifier 50 to indicate a procedure was performed bilaterally, the modifiers LT (Left) and RT (Right) should not be billed on the same service line.  Modifiers LT or RT should be used to identify which one of the paired organs were operated on.  Billing procedures as two lines of service using the left (LT) and right (RT) modifiers are not the same as identifying the procedure with Modifier 50. An example of inappropriate will be: 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.

This modifier can be the cause of several errors. First, some CPT codes have laterality built into the code descriptor, rendering the use of modifier 50 (Bilateral procedure) redundant. Second, some payers, including Medicare, prefer you to use Level II (HCPCS) modifiers RT (Right side) and LT (Left side) to specify the side of the body on which your provider performed the service.

How you should use it: Make sure you know your payer’s preference before using 50, RT, or LT. You can also check to see which CPT codes will take 50 by

  • going to the Physician Fee Schedule Search page;
  • entering a valid CPT code number;
  • checking All modifiers in the appropriate drop-down;
  • hitting Search;
  • clicking the Show All Columns link;
  • Then scrolling over to the BILT SURG column.

You should never attach 50 to codes with indicators 0, 2, and 9 in that column; however, you can use the modifier on codes with indicators 1 or 3.

Example1: Procedure code 19303 (Mastectomy, simple, complete) is performed bilaterally, report the service as 19303 and append modifier 50.

Example2: A physician performs removal of impacted cerumen with instrumentation on both ears. You report 69210 (Removal impacted cerumen requiring instrumentation, unilateral) for the procedure, and append modifier 50 to 69210 to show the procedure was bilateral as the 69210 descriptor contains the word “unilateral,” and is thus a modifier 50 opportunity.