Available online 15 September 2025, 101135

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The use of supplementary codes to adjust primary billing codes that describe surgical services are a source of potential deserved additional revenue. The American Medical Association (AMA) maintains the Current Procedural Technology (CPT®) set of codes which include “modifier” codes that are used in addition to primary procedure codes. The Centers for Medicare and Medicaid (CMS) maintains a set of G codes which are part of the Healthcare Common Procedural Coding System (HCPCS). Both sets of codes are complex, extensive and have requirements in appropriate use and documentation, but successful use can improve financial reflection of the full extent of the services provided in colorectal practice. This article explores both CPT® modifiers and G codes and provides the reader a summary of the most relevant codes along with their appropriate uses and tips for successful application in practice.

Section snippetsProcedural modifiers

The first main category of modifiers is those that are applied to procedural codes.

Procedural variation modifiers

A group of modifiers of particular importance are those used to describe variations in procedural services. Modifier 22 specifies increased procedural services and is among the most used and most financially important procedural modifiers. It denotes substantial additional work beyond the usual effort associated with the base CPT® code and can frequently be appropriate in the complex surgeries used in colorectal surgery. Modifier 22 can be applied for extended operative time or for additional

Multiple procedure modifiers

Modifier 51 specifies multiple procedures by a single provider within one encounter. This may allow billing of a second separate procedure that would not otherwise be billable, such as a separate small bowel resection at the time of a colectomy. Procedures after the first will likely reimburse at a reduced rate; for optimal reimbursement, the most resource-intensive, highest reimbursement CPT® code should be listed first, with additional codes receiving modifier 517. Successful use of this

Procedural collaboration modifiers

Modifier 62 specifies two surgeons and is used when two surgeons from different specialties work together, each as a primary surgeon, each performing and documenting their own distinct parts of a procedure, but each billing the same comprehensive CPT® code. Each surgeon should expect 62.5 % of the usual reimbursement. Modifier 66 specifies a surgical team and is used the same way, but can be used to specify three or more surgeons, with each separately billing and documenting their parts of the

Other procedural

Modifier 26 specifies professional component of procedural services, indicating performance of non-technical services related to the procedure while omitting the technical aspect of the procedure. This code is more commonly used in some other specialties, but rarely in colorectal surgery. The most routine use of this modifier is in radiology, for primary interpretation of a study where the physician did not perform the study. This concept could be applied to certain types of diagnostic studies

Evaluation and management modifiers

A second major category of particularly important CPT® code modifiers are those applied to Evaluation and Management (E/M) codes to specify special circumstances or variations of service.

Periprocedural evaluation and management modifiers

Modifier 25 is among the most used modifiers, and specifies significant, separately identifiable (E/M) services by the same physician (or physician group) on the same day of a procedure or other service. This code is particularly useful in colorectal surgery when performing office or in-hospital E/M services along with an in-office/bedside/point of care minor procedural service that is billable via CPT® code, such as performing an office consultation including an anoscopy or sigmoidoscopy; in

Collaborative evaluation and management modifiers

Modifier GC, as mentioned above, can be used to specify resident physician participation and contribution to E/M services.

Modifier FS specifies split/shared evaluation and management (E/M) between an MD and an advanced practice provider (APP) such as a nurse practitioner or physician assistant on same patient on same date within a facility setting. For instance, if an APP performs an E/M service for a patient (such as seeing a consult) and writes a note, and later an attending physician sees

Telehealth services

Modifiers 93 and 95 indicate E/M services provided via telehealth, via phone (93) or via video (95). These can be applied to the appropriate level of E/M service as documented. Telemedicine coding has been rapidly changing over the past few years including new telemedicine CPT® codes (98,000–98,007), with some payers using these codes and others possibly using modifiers 93 and 95 to provide full reimbursement of associated E/M codes21,22; this area may be subject to further significant changes.

Cancer screening related services

Modifier 33 specifies preventative services whose primary purpose is evidence-based service recommended by the US Preventative Services Task Force and can be applied to both procedural and E/M codes. This can be utilized in colorectal surgery to specify that a colonoscopy is for screening purposes, ensuring no cost to the patient as specified by the Affordable Care Act; without this modifier, the patient may be billed.23 Modifier 33 should only be applied to non-Medicare beneficiaries; G-codes

G codes

The Centers for Medicare and Medicaid (CMS) G codes are a set of Healthcare Common Procedure Coding System (HCPCS) codes which exist to report medical services and procedures that aren’t described in the Current Procedural Terminology (CPT®) code set. The G code set is maintained by CMS as opposed to the CPT® code set which is maintained by the American Medical Association (AMA). The codes are alphanumeric and start with a G followed by four numbers. These codes are generally used for Medicare

Disclosures

KT: None.

DF: None.

Author information

Daniel R. Fish M.D., M.S. Colorectal Surgery and Director of GI Surgical Quality

Kelly M. Tyler, M.D., Division Chief of Colorectal Surgery and Professor of Surgery

Acknowledgements

Ms. Jenny Maus, Billing and Coding Specialist; UMMS-Chan Baystate, Springfield, MA

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