Summary & Overview

HCPCS G0455: Preparation and Instillation of Fecal Microbiota

HCPCS Level II code G0455 denotes preparation with instillation of fecal microbiota by any method and includes assessment of the donor specimen. The code captures services related to fecal microbiota transplantation (FMT), a therapeutic procedure used to restore gut microbial balance in patients with certain gastrointestinal conditions. Nationally, accurate coding for this service matters for payer coverage determinations, clinical tracking, and public health surveillance as interest in microbiome-based therapies grows.

Key payers in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of the code’s clinical scope, typical sites of service, and the kinds of benchmarks and policy elements commonly associated with FMT billing. The publication summarizes prevailing coverage considerations, coding practice notes, and operational implications for providers and billing teams.

This piece provides: (1) a clinical and coding summary of G0455; (2) benchmarking context for commonly involved payers; and (3) a policy and operational primer to support appropriate documentation and claims submission. Data not available in the input are explicitly noted where applicable.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicareG0455HCPCS Level IIfecal microbiota transplantationmicrobiota instillationoutpatient proceduresprocedure codingclinical billinginfection-related therapy

Billing Code Overview

HCPCS Level II code G0455 covers preparation with instillation of fecal microbiota by any method, including assessment of donor specimen. This service includes the processes necessary to prepare and administer fecal microbiota material to a recipient and incorporates evaluation of the donor specimen as part of the preparation workflow.

Service type: Microbiota transplantation procedure, including preparation and instillation
Typical site of service: Ambulatory clinics, outpatient procedural suites, infusion or endoscopy units, and other settings where instillation procedures are performed

Data not available in the input.

Clinical & Coding Specifications

Clinical Context

A typical patient is a 62-year-old adult with recurrent Clostridioides difficile infection who has failed multiple courses of appropriate antibiotic therapy. After infectious disease and gastroenterology evaluation, the patient is scheduled for fecal microbiota transplantation (FMT). The clinical workflow begins with donor screening and specimen preparation in the laboratory, including infectious disease testing and stool processing. On the day of treatment the patient is prepped in an outpatient endoscopy suite or ambulatory procedure room: informed consent is confirmed, baseline vital signs documented, and any procedural sedation or anesthesia is administered as indicated. The FMT material is instilled by colonoscopic infusion into the cecum or via retention enema depending on clinical judgment and patient factors. Post-procedure monitoring includes assessment for immediate adverse events, documentation of donor specimen testing, and follow-up visits to assess resolution of infection and any delayed complications. Typical sites of service include outpatient hospital endoscopy units, ambulatory surgical centers, or hospital inpatient units when the patient is already admitted.

Coding Specifications

Modifier	Description	When to Use
`11`	Office or other outpatient visit	Use when the FMT is performed in an outpatient clinic visit setting where `G0455` is billed and the visit is the primary service.
`22`	Increased procedural services	Use when documented work or complexity substantially exceeds usual requirements for preparation and instillation.
`23`	Unusual anesthesia	Use when general anesthesia or an unusual form of anesthesia is required for the FMT procedure.
`52`	Reduced services	Use when the procedure is partially reduced or not completed as planned.
`53`	Discontinued procedure	Use when the FMT is started but terminated before completion for documented medical reasons.
`59`	Distinct procedural service (Note: not in provided list)	Data not available in the input.
`62`	Two surgeons	Use when two qualified providers actively participate in a complex FMT procedure requiring shared surgical responsibilities.
`66`	Surgical team	Use when a surgical team approach is documented for the FMT instillation procedure.
`78`	Return to operating/procedure room for a related procedure during the global period	Use when a repeat instillation or related endoscopic procedure is performed shortly after an initial FMT due to complication.
`80`	Assistant surgeon	Use when an assistant surgeon is documented assisting with the FMT delivered via colonoscopy.
`81`	Minimum assistant surgeon	Use for documented minimal assistance during the procedure.
`82`	Assistant surgeon (qualified resident)	Use when a resident provides assistance and meets reporting criteria.
`AS`	Accredited outpatient surgical center	Use to indicate the service was rendered in an Ambulatory Surgical Center when required by payors.
`QK`	Medical direction of two, three, or four concurrent anesthesia procedures	Use when the physician provides medical direction for concurrent anesthesia while the FMT is performed under anesthesia.

Taxonomy Code	Specialty	Notes
`207Q00000X`	Gastroenterology	Gastroenterologists commonly perform colonoscopic instillation of fecal microbiota.
`207L00000X`	Infectious Disease	Infectious disease specialists oversee donor screening and indications for FMT for recurrent C. difficile.
`208600000X`	Colon & Rectal Surgery	Colorectal surgeons may perform FMT, particularly when combined with other colorectal procedures.
`207K00000X`	Family Medicine	Family physicians may coordinate outpatient FMT care, referrals, and follow-up in some settings.
`207R00000X`	Internal Medicine	Hospitalists or internists may be involved when FMT is provided during inpatient care.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`A04.7`	Enterocolitis due to Clostridioides difficile	Primary indication for FMT in recurrent or refractory infection.
`K52.9`	Noninfective gastroenteritis and colitis, unspecified	May be listed when the clinical diagnosis is colitis of uncertain etiology considered for microbiota therapy.
`K57.30`	Diverticulosis of large intestine without perforation or abscess	May be a comorbidity affecting procedural approach for instillation by colonoscopy.
`R19.4`	Change in bowel habit	Symptom code that can be associated with conditions prompting consideration of microbiome-based therapies.
`U07.1`	COVID-19, virus identified	Use when active COVID-19 infection affects donor screening or timing of elective FMT procedures.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`45378`	Colonoscopy, flexible; diagnostic, including collection of specimen(s) by brushing or washing, when performed (separate procedure)	Often used when FMT is delivered via colonoscopic instillation; documents the colonoscopy portion of the encounter when billed separately under applicable payer rules.
`45380`	Colonoscopy, flexible; with biopsy, single or multiple	May be reported if mucosal biopsies are obtained during the same colonoscopic session as FMT instillation.
`99213`	Office or other outpatient visit for the evaluation and management of an established patient, typically 15 minutes	Commonly used for pre-procedure evaluation or routine follow-up visits related to FMT when appropriate.
`96372`	Therapeutic, prophylactic, or diagnostic injection (specify substance or drug); subcutaneous or intramuscular	Use if any injection or instillation (non-endoscopic) approach is used and a payer requires a contemporaneous injection code (use per payer guidance).
`99152`	Moderate sedation services provided by the same physician or other qualified health care professional performing the diagnostic or therapeutic service, initial 15 minutes	Report when moderate sedation is provided by the FMT-performing physician during the procedure and payer rules permit separate reporting.