Summary & Overview

HCPCS G0328: Colorectal Cancer Screening, Fecal Occult Blood Immunoassay

HCPCS Level II code G0328 represents an immunoassay-based fecal occult blood test (FOBT) for colorectal cancer screening, billed for one to three simultaneous tests. This screening modality is a widely used, noninvasive option for population-level detection of occult gastrointestinal bleeding and supports early identification of colorectal neoplasia. Nationally, FOBT-based screening remains a relevant component of colorectal cancer prevention strategies, especially in ambulatory and outpatient laboratory settings.

Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise discussion of clinical context for immunoassay FOBT screening, typical sites of service, and the role of this code in billing workflows. The publication also outlines benchmarks and policy considerations relevant to payers and providers, including coverage norms and documentation requirements where available.

This summary provides a practical reference for coding and administrative staff, laboratory directors, and policy analysts seeking a clear description of what G0328 denotes, how it is commonly used in practice, and which major payers are engaged with this screening service. Data not available in the input are noted as such in relevant sections.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicareG0328HCPCS Level IIcolorectal cancer screeningfecal occult blood testimmunoassaylaboratoryoutpatientscreening

Billing Code Overview

HCPCS Level II code G0328 describes colorectal cancer screening using a fecal occult blood test (FOBT) by immunoassay, billed for 1–3 simultaneous tests. This service is a noninvasive laboratory screening method intended to detect occult blood in stool as part of colorectal cancer screening programs.

Service type: Laboratory diagnostic screening test
Typical site of service: Outpatient laboratory or clinic setting where stool samples are collected and processed for immunoassay-based fecal occult blood testing

Clinical & Coding Specifications

Clinical Context

A 58-year-old average-risk adult presents to a primary care clinic for routine colorectal cancer screening. The clinician provides an immunochemical fecal occult blood test kit and documents the preventive service. The patient collects 1–3 stool specimens at home and returns them for laboratory immunoassay analysis. The clinic or laboratory bills G0328 for the colorectal cancer screening fecal immunoassay. Typical workflow: patient counseling and order placed during the office visit; specimen collection instructions provided; specimens processed by the performing laboratory or point-of-care immunoassay; results documented in the electronic health record and communicated to the patient; positive results trigger referral for diagnostic colonoscopy and appropriate diagnostic coding and follow-up.

Coding Specifications

Modifier	Description	When to Use
`GZ`	Service/item expected to be denied as not reasonable and necessary	Use when the provider believes the screening test is not reasonable/necessary and no ABN is on file (rare for screening).
`GA`	Waiver of liability statement on file (Advanced Beneficiary Notice)	Use when an ABN/waiver is obtained from the beneficiary for services that may not be covered.
`GY`	Item or service statutorily excluded or does not meet the definition of any Medicare benefit	Use when the screening immunoassay is not a covered service for the specific payer plan.
`QW`	CLIA waived test performed in a waived setting	Use when the fecal immunoassay is performed as a CLIA-waived point-of-care test.
`TC`	Technical component	Use when billing only the laboratory/technical component of the test (facility/lab performs assay).
`26`	Professional component	Use when billing only the professional component (result interpretation or professional oversight) separate from the lab.
`59`	Distinct procedural service	Use to indicate a separate and distinct service when another unrelated service was performed on the same day.
`91`	Repeat clinical diagnostic laboratory test	Use when the test is repeated on the same day to confirm initial result.
`52`	Reduced services	Use when the test was partially reduced or not performed as typically described.
`90`	Reference (outside) laboratory	Use when the specimen was sent to an outside/reference laboratory for testing.
`53`	Discontinued procedure	Use when specimen collection or testing was started but discontinued and cannot be completed.
`23`	Unusual anesthesia	Not typically applicable to this noninvasive test; rarely used if performed in conjunction with a procedure requiring anesthesia.
`73`	Discontinued outpatient hospital/ambulatory surgery prior to anesthesia	Not applicable for routine fecal immunoassay; included when billing rules require.
`78`	Return to operating room for related procedure during postoperative period	Not applicable to this screening test; rarely used in related procedural workflows.

Taxonomy Code	Specialty	Notes
207Q00000X	Family Medicine	Primary care clinicians ordering and providing screening and specimens.
207R00000X	Internal Medicine	Internists who order colorectal screening tests and manage results.
208D00000X	Gastroenterology	Specialists who interpret positive screening results and perform follow-up colonoscopy.
207L00000X	Preventive Medicine	Clinicians focused on cancer screening programs and preventive care.
332B00000X	Clinical Laboratory	Laboratory providers performing the immunoassay (note: use appropriate lab taxonomy).

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`Z12.11`	Encounter for screening for malignant neoplasm of colon	Primary screening indication for fecal immunoassay in asymptomatic adults.
`R19.5`	Other fecal abnormalities	Symptom that may prompt use of fecal occult blood testing when present.
`K92.1`	Melena	Overt GI bleeding sign that may lead to diagnostic FOBT or other testing.
`K92.2`	Gastrointestinal hemorrhage, unspecified	Symptom/diagnosis prompting stool blood testing as part of evaluation.
`Z80.0`	Family history of malignant neoplasm of digestive organs	Increased risk factor leading to more frequent or earlier screening using fecal immunoassay.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`82270`	Blood, occult, by fecal immunoassay, qualitative; single specimen	Common laboratory CPT for a single-specimen fecal immunoassay performed in a clinical laboratory; may be billed by labs when local payor rules align.
`82274`	Blood, occult, by peroxidase activity (e.g., guaiac), qualitative, 3 specimens	Alternative FOBT method (guaiac) historically used for screening; not the immunoassay method but relevant when comparing tests.
`G0104`	Colorectal cancer screening; fecal occult blood test, including patient education and test administration, done by a laboratory	Medicare national screening G-code historically used for FOBT screening; related in screening workflows.
`45378`	Colonoscopy, flexible; diagnostic, with or without collection of specimen(s) by brushing or washing, biopsy(s), or polypectomy	Diagnostic follow-up procedure commonly performed when `G0328` results are positive.
`45385`	Colonoscopy with removal of tumor(s), polyp(s), or other lesion(s) by snare technique	Therapeutic colonoscopy code used when polyps are found during diagnostic colonoscopy after a positive stool test.