Code Carefully for Bilateral Procedures

Coding for bilateral procedures can be confusing. Many payers accept CPT modifier 50 as an indicator of a bilateral procedure, but they differ in how they apply it to their coding and payment policies.

First, let's look at what CPT says: Unless otherwise identified in the listings, bilateral procedures that are performed at the same session should be identified by adding modifier 50 to the appropriate 5-digit code.

Below is a brief look at the policies of top payers. But first, NOTE: under ICD-10, many diagnosis codes are anatomically specific. Take that into consideration when deciding which modifier would be appropriate. For example:

Example 1
25515 Treat Fracture of Radius
DX: S52.302A Unspecified fracture of shaft of RIGHT radius, initial encounter 

Modifier 50 or LT would not be appropriate in the above situation 

Example 2
25515 Treat Fracture of Radius
S52.301A Unspecified fracture of shaft of LEFT radius, initial encounter
S52.302A Unspecified fracture of shaft of RIGHT radius, initial encounter 

Modifier 50 would be appropriate.



Definition: Medicare contractor Novitas Solutions defines bilateral surgeries as procedures performed on both sides of the body during the same operative session or on the same day. CMS has defined codes subject to the bilateral payment rule. To verify if a code is subject to the bilateral payment policy, search the code on the Medicare fee schedule using this tool. (Need help? See How to Use the Searchable Medicare Physician Fee Schedule Booklet [PDF]).

Coding notes: Report the procedure code with modifier 50. Report a "1" in the number-of-services field. For example, if you are billing for a bilateral mastectomy, you would report CPT code 19303 (Mastectomy, simple, complete) with the modifier. You would report the service as a single line item: 19303 50.

Do not report modifier 50 with procedure codes whose terminology is indicative of unilateral or bilateral services because these codes are bilateral by definition. Examples are code 27395 (Lengthening of hamstring tendon; multiple, bilateral) and code 52290 (Cystourethroscopy; with ureteral meatotomy, unilateral or bilateral).

How it pays: Medicare pays claims reporting bilateral procedures based on 150 percent of the Medicare Physician Fee Schedule fee amount. The limiting charge is 115 percent of that amount. Certain procedures are not applicable to the 150-percent payment rule for bilateral procedures; payment is based on 100 percent of the fee schedule for each side, e.g., ophthalmoscopy codes 92225 and 92226. When performed bilaterally, these codes should be reported with modifiers RT (right)-LT (left) or modifier 50 to ensure proper payment. Procedure codes containing the terms "bilateral" or "unilateral or bilateral" in their definitions are not subject to bilateral pricing. Payment for these services is based on 100 percent of the fee schedule for a surgical code.

For details, see the Medicare Reference Manual on the Novitas website.


Coding notes: When a bilateral procedure is performed and an appropriate bilateral code is not available, use a unilateral code. Bill the unilateral code twice with a quantity of 1 for each code. For all procedures, use modifiers LT and RT as appropriate. For example, bilateral application of short leg cast is billed as follows:

Procedure Code          Modifier
29405                          LT
29405                          RT

This policy is in the Texas Medicaid Provider Procedures Manual (PDF), Check the manual for instruction about coding for specific procedures.


Definition: A surgical procedure is considered bilateral when the same procedure is performed on both sides of the body. Common anatomical sites for bilateral surgical procedures are extremities, eyes, ears, and breasts.

Coding note: When billing Aetna for a bilateral procedure, enter the code twice on two separate claim lines, once with modifier 50 and once without.

How it pays: Aetna determines the order of multiple surgical procedures on the basis of the relative value units of each procedure for the appropriate place of service (facility versus non-facility) under the Medicare Physician Fee Schedule. When a surgeon performs bilateral surgery, or a combination of both bilateral and multiple surgeries, Aetna calculates the allowable benefit as follows (in the same manner as for multiple surgery):

100 percent for the procedure with the highest RVU +
50 percent for the procedure with the second highest RVU +
25 percent for each subsequent procedure.


Definition: Bilateral procedures are those 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).

Coding notes: Blue Cross and Blue Shield of Texas (BCBSTX) follows the CPT guideline, which states that the intent of modifier 50 is to be appended to the appropriate unilateral procedure code as a one-line entry on the claim form indicating the procedure was performed bilaterally (two times). For example: 

Procedure Code      Billed Amount       Units/Days
##### - 50                      $$$                         1                                         

When using modifier 50 to indicate a procedure was performed bilaterally, do not bill the modifiers LT and RT on the same service line. Use modifiers LT or RT to identify which one of the paired organs was operated on. Billing procedures as two lines of service using the LT and RT modifiers is not the same as identifying the procedure with modifier 50. Modifier 50 is the coding practice of choice when reporting bilateral procedures to BCBSTX. 

How it pays: The BCBSTX /HMO Blue Texas multiple surgery pricing guidelines apply. For multiple surgeries, the primary surgical procedure is adjudicated at 100 percent of the allowable amount, and each subsequent surgical procedure performed (regardless of anatomic area) is adjudicated at 50 percent of the allowable amount. Thus bilateral surgical procedures are priced at 150 percent of the allowable amount.


Definition: Modifier 50 is used to report procedures performed on both sides of the body (mirror image) during the same operative session. It is only applicable to services and/or procedures performed on identical anatomical sites, aspects, or organs.

Coding notes: List the procedure code once with modifier 50. For surgical codes, list the number of units as "1"; for nonsurgical codes, list the number of units as "2." Do not use modifier 50 to report surgical procedures identified by their CPT descriptor as bilateral or unilateral. Do not use modifier 50 with modifiers RT and LT. If the CPT code descriptor indicates a bilateral procedure (and there is no CPT code for unilateral procedure), and the procedure was only performed on one side, it is appropriate to use modifiers RT or LT with modifier 52 (Reduced Services). RT and LT may be used without modifier 50 but not in addition to modifier 50.

If there are CPT codes specific to the procedure, one for unilateral and one for bilateral, the bilateral code would be appropriate for use if the procedures were performed during the same operative session by the same physician. CPT codes that can be reported with modifier 50, when appropriate, are 10021-69990 (Surgery), 70010-79999 (Radiology), and 90281-99199 (Medicine). Note: Not all codes within these ranges are applicable.

How it pays: Cigna pays at 100 percent of the fee schedule or usual and customary (U&C)/maximum reimbursable charge (MRC) for the first surgical procedure and 50 percent for the second surgical procedure.

Bilateral radiology is paid at 200 percent of the fee schedule or U&C/MRC when billed with modifier 50 and "2" units on one line. Bilateral radiology is paid at 100 percent when billed with modifiers RT/LT on separate lines with "1" unit per line.

Multiple, bilateral procedures follow multiple surgery guidelines outlined in Cigna's modifier 51 policy (with the exception of multiple radiology imaging services for contiguous body parts).


Definition: Humana refers to American Medical Association guidelines: "Modifier 50 is used to report bilateral procedures that are performed at the same operative session" (by the same physician). "Bilateral procedures are procedures typically performed on both sides of the body."

Coding note: Humana recognizes bilateral modifier 50 or modifiers RT and LT appended to procedure codes as applicable for commercial and Medicare Advantage plans.  Humana’s code edits require the use of these anatomical modifiers to designate the area or part of the body on which the procedure is performed.

How it pays: Humana recognizes as two services but processes as one unit a single claim line containing an inherently unilateral CPT code billed with modifier 50. Humana pays such a claim at 150 percent of the allowable. When claims are billed with two or more of the same inherently unilateral CPT codes where any line contains the modifier 50, the first line containing modifier 50 is paid at 150 percent and all subsequent lines with the same CPT code are denied.

If an inherently bilateral procedure is submitted with a modifier 50, Humana pays at 100 percent. If a code is categorized as both unilateral/bilateral and submitted with a modifier 50, Humana considers the code as an inherently bilateral code and pays at 100 percent.

The applicable bilateral surgery increase (150 percent) will be applied before multiple surgery reduction logic based on highest base allowable. Commercial standard multiple surgery policy is 100/50/25.

See details in Humana's claims policy document.

United Healthcare

Definition: Bilateral procedures are those that can be performed on both sides of the body during the same session by the same individual physician.

Coding notes: Procedure codes bilateral in their intent or with bilateral written in their description should not be reported with the bilateral modifier 50, or modifiers LT and RT, because the code is inclusive of the bilateral procedure. The UnitedHealthcare Bilateral Eligible Procedures Policy List is developed based on the Medicare Physician Fee Schedule relative value file status indicators.

How it pays: A unilateral surgical code reported with modifier 50 is eligible for payment at 150 percent of the allowable, with one side paid at 100 percent and the other side at 50 percent. When other reducible procedure codes are reported on the same date of service, an additional multiple procedure/imaging reduction may or may not be applied to the line paid at 100 percent, depending on whether another procedure code is ranked as primary or not. A nonsurgical code reported with modifier 50 will be eligible for payment at 100 percent of the allowable amount for each side for a sum of 200 percent of the allowable amount.

See UnitedHealthcare's Bilateral Procedures Policy for details (PDF).

If you have questions about billing and coding or payer policies, contact the reimbursement specialists at for help, or call the TMA Knowledge Center at (800) 880-7955. TMA members can use the TMA Hassle Factor Log to help resolve insurance-related problems.

Published April 8, 2014

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