Know the Right Use of Modifiers 51 and 59

by | Published on Dec 14, 2020 | Specialty Billing

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Correct and appropriate use of modifiers is important to file accurate claims and thus receive correct payments. Modifiers enable surgeons to effectively meet payment policy requirements established by the insurers. Wrong use of modifiers is one of the most common GI coding mistakes. In gastroenterology coding and in other specialty coding, when the same surgeon performs multiple procedures in the same operative setting, often there is confusion about using modifier 51 (Multiple procedures) or modifier 59 (Distinct procedural service).

Known as surgical modifiers, modifiers 51 and 59 are both used when multiple services are performed during a single encounter. However, they serve different purposes.

Modifier 51 can be used to report multiple surgeries performed on the same day, during the same surgical session. It is used to identify the second and subsequent procedures to third party payers. The modifier would be applied to any secondary procedures performed. It can be used to document two procedures in two different coding categories performed on the same day, just like EGD and colonoscopy.

To report this modifier right, the coder should list the procedure with the highest RVU (highest paying) first, and use modifier 51 on the subsequent service(s) with lower RVU (lowest paying).

The American Society of Anesthesiologists says that Modifier 51 applies to:

    • Different procedures performed at the same session
    • A single procedure performed multiple times at different sites
  • A single procedure performed multiple times at the same site

It is not to be used when a procedure is performed along with an Evaluation and Management (E/M) service. There are instances where multiple procedures are performed but modifier 51 is not appropriate. Modifier 51 is not appended to add-on codes like CPT code 64462.


Modifier 59

Modifier 59 refers to Distinct Procedural Service which indicates that a procedure is separate and distinct from another procedure provided on the same date of service. According to CMS, “Modifier 59 is an important NCCI-associated modifier that is often used incorrectly.” Modifier 59 helps to identify procedures/services, other than E/M services, that are not normally reported together, but are appropriate under the circumstances. It can be used for different session or encounter on the same date of service and different procedure, distinct from the first procedure.

To use this modifier, provider’s documentation has to support different session, different procedure or surgery, different site or organ system, separate incision/excision, separate lesion, or separate injury, which is not ordinarily encountered or performed on the same day by the same individual. CMS recommends this modifier should only be used to identify clearly independent services that represent significant departures from the usual situations described by the NCCI edit.

CMS reports other three specific appropriate uses of modifier 59, as –

  • for two services described by timed codes provided during the same encounter only when they are performed sequentially
  • for a diagnostic procedure which precedes a therapeutic procedure only when the diagnostic procedure is the basis for performing the therapeutic procedure
  • for a diagnostic procedure which occurs subsequent to a completed therapeutic procedure only when the diagnostic procedure is not a common, expected, or necessary follow-up to the therapeutic procedure

Coders must make sure not to use modifier 59 when a more appropriate modifier is available. Earlier, modifiers XE, XP, XS and XU were used along with modifier 59. But now, these modifiers are not required but may be used instead of modifier 59 when appropriate.

Modifier 51 vs Modifier 59


Modifier 51

  • Multiple procedures
  • Extra procedure in same session
  • Extra procedure in different site

Modifier 59

  • Distinct procedures
  • Separate procedure in different sessions
  • Distinct procedure in different site

While there are differences in usage between modifier 51 and 59, there are certain similarities too.

Both the modifiers –

  • should not be applied to an E/M service
  • have payment implications

Modifier 51 impacts the payment amount, and modifier 59 affects whether the service will be paid at all. Medical billing companies as well as medical practices should take effort to use the right modifiers on the medical claims and thus prevent claim denials and reimbursement issues.

Meghann Drella

Meghann Drella possesses a profound understanding of ICD-10-CM and CPT requirements and procedures, actively participating in continuing education to stay abreast of any industry changes.

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