G9998 HCPCS code: Documentation of medical reason(s) for an interval of less than 3 years since the last colonoscopy (e.g., last colonoscopy incomplete, last colonoscopy had inadequate prep, piecemeal removal of adenomas, or sessile serrated polyps >= 20 mm in size, last colonoscopy found greater than 10 adenomas, lower gastrointestinal bleeding, or patient at high risk for colon cancer due to underlying medical history ([i.e. crohn's disease, ulcerative colitis, personal or family history of colon cancer, hereditary colorectal cancer syndromes])
G9998 is the HCPCS Level II code for documentation of medical reason(s) for an interval of less than 3 years since the last colonoscopy (e.g., last colonoscopy incomplete, last colonoscopy had inadequate prep, piecemeal removal of adenomas, or sessile serrated polyps >= 20 mm in size, last colonoscopy found greater than 10 adenomas, lower gastrointestinal bleeding, or patient at high risk for colon cancer due to underlying medical history ([i.e. crohn's disease, ulcerative colitis, personal or family history of colon cancer, hereditary colorectal cancer syndromes]). Its Medicare coverage code is C (Carrier judgment): Coverage is decided by the Medicare contractor (MAC) case by case.
Code details
| Field | Value |
|---|---|
| Section | G codes — Procedures and professional services (temporary) |
| Coverage code | C — Carrier judgment |
| Pricing indicator | 00 — Not separately priced by Medicare |
| BETOS category | Z2 |
| Added | 2022-01-01 |
| Last action effective | 2024-01-01 |
Medicare policy articles for this code
- A56632: Billing and Coding: Colonoscopy/Sigmoidoscopy/Proctosigmoidoscopy (Palmetto GBA (MAC - Part A, MAC - Part B))
Covered diagnoses (558 ICD-10-CM codes)
The diagnoses most often listed as covered in the policy articles above:
| ICD-10-CM | Diagnosis | Articles listing it |
|---|---|---|
| A03.9 | Shigellosis, unspecified | 1 |
| A04.3 | Enterohemorrhagic Escherichia coli infection | 1 |
| A04.5 | Campylobacter enteritis | 1 |
| A04.6 | Enteritis due to Yersinia enterocolitica | 1 |
| A04.71 | Enterocolitis due to Clostridium difficile, recurrent | 1 |
| A04.72 | Enterocolitis due to Clostridium difficile, not specified as recurrent | 1 |
| A04.8 | Other specified bacterial intestinal infections | 1 |
| A04.9 | Bacterial intestinal infection, unspecified | 1 |
| A06.1 | Chronic intestinal amebiasis | 1 |
| A06.2 | Amebic nondysenteric colitis | 1 |
Showing 10 of 558. The full list, non-covered diagnoses and CSV export are in Caduvo.
What changed for G9998
- 2022-01-01: G9998 added to HCPCS Level II
- Next scheduled CMS quarterly update (HCPCS and DMEPOS fee schedule): 2027-01-01
Frequently asked questions
What is HCPCS code G9998?
G9998 is the HCPCS Level II code for documentation of medical reason(s) for an interval of less than 3 years since the last colonoscopy (e.g., last colonoscopy incomplete, last colonoscopy had inadequate prep, piecemeal removal of adenomas, or sessile serrated polyps >= 20 mm in size, last colonoscopy found greater than 10 adenomas, lower gastrointestinal bleeding, or patient at high risk for colon cancer due to underlying medical history ([i.e. crohn's disease, ulcerative colitis, personal or family history of colon cancer, hereditary colorectal cancer syndromes]). Short descriptor: "Doc med rsn <3 colon".
Does Medicare cover G9998?
Coverage code C — Carrier judgment. Coverage is decided by the Medicare contractor (MAC) case by case.
Which diagnoses support coverage for G9998?
Medicare policy articles that cite G9998 list 558 covered ICD-10-CM diagnosis codes across 1 article. The most cited include A03.9 (Shigellosis, unspecified), A04.3 (Enterohemorrhagic Escherichia coli infection), A04.5 (Campylobacter enteritis). A listed diagnosis is necessary but not sufficient; the policy's other criteria still apply.
Related G99 codes
- G9900 — Screening, diagnostic, film, digital or digital breast tomosynthesis (3d) mammography results were not documented and reviewed, reason not otherwise specified
- G9901 — Patient age 66 or older in institutional special needs plans (snp) or residing in long-term care with pos code 32, 33, 34, 54, or 56 for more than 90 consecutive days during the measurement period
- G9902 — Patient screened for tobacco use and identified as a tobacco user
- G9903 — Patient screened for tobacco use and identified as a tobacco non-user
- G9904 — Documentation of medical reason(s) for not screening for tobacco use (e.g., limited life expectancy, other medical reason)
- G9905 — Patient not screened for tobacco use
- G9906 — Patient identified as a tobacco user received tobacco cessation intervention during the measurement period or in the six months prior to the measurement period (counseling and/or pharmacotherapy)
- G9907 — Documentation of medical reason(s) for not providing tobacco cessation intervention on the date of the encounter or within the previous 12 months (e.g., limited life expectancy, other medical reason)
- G9908 — Patient identified as tobacco user did not receive tobacco cessation intervention during the measurement period or in the six months prior to the measurement period (counseling and/or pharmacotherapy)
- G9909 — Documentation of medical reason(s) for not providing tobacco cessation intervention on the date of the encounter or within the previous 12 months if identified as a tobacco user (e.g., limited life expectancy, other medical reason)
- G9910 — Patients age 66 or older in institutional special needs plans (snp) or residing in long-term care with pos code 32, 33, 34, 54 or 56 for more than 90 consecutive days during the measurement period
- G9911 — Clinically node negative (t1n0m0 or t2n0m0) invasive breast cancer before or after neoadjuvant systemic therapy
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Next steps
- Run a reimbursement report for a device billed under G9998
- Watch G9998 for fee, coverage and descriptor changes
- Build a full Medicare revenue model for G9998
Sources: CMS HCPCS Level II release October 2025; CMS DMEPOS fee schedule; CMS NCCI MUE tables; CMS Medicare utilization (physician and DME supplier files); CMS Medicare Coverage Database articles. Fees are Medicare allowables, not commercial rates. Not billing or legal advice.