Professional services (CMS-defined procedures)
G9998 — 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])
HCPCS code G9998 is used on U.S. medical bills for professional services (cms-defined procedures): 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]).
- Typical setting: Outpatient
- National avg charge (illustrative): Medicare physician fee schedule — see CMS lookup tool.
- Most-disputed reason: Service billed at a level not supported by documentation
What it means
What G9998 actually means
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]).
The official CMS HCPCS Level II descriptor for this code is shown above. If the description on your bill does not match the service you actually received, that is a reason to ask for the itemized bill and dispute the line.
Common errors with this code
What goes wrong on real bills.
Most bills that look correct still contain at least one of these issues. Up to 49% of medical bills contain errors (CFPB).
- Quantity or units of service that exceed what the medical record supports.
- Duplicate billing on the same date of service.
- Missing or incorrect modifier (e.g., JW for drug waste, RT/LT for sides).
- Service billed at a level not supported by documentation without supporting documentation.
If you see G9998 on your bill
Three steps before paying.
1. Get the itemized bill. If your statement only shows a summary, request the CPT-level itemized bill before paying. Generate the request language →
2. Cross-check against the EOB. Compare what your insurer's Explanation of Benefits says you owe versus what the hospital is asking. They disagree more often than people think. Read the bill-vs-EOB guide →
3. Run a free Bill Scan. Upload the bill (and EOB if you have it) and BillBusted will flag the most likely issues with this specific code in your specific state. Run free scan →
Related codes
Other codes in this category.
People who land on G9998 often also see these adjacent codes on the same bill.
HCPCS
G0011 — Individual counseling for pre-exposure prophylaxis (prep) by physician or qualified health care professional (qhp) to prevent human immunodeficiency virus (hiv), includes hiv risk assessment (initial or continued assessment of risk), hiv risk reduction and medication adherence, 15-30 minutes
Hiv prep counsel, md 15-30m
HCPCS
G0012 — Injection of pre-exposure prophylaxis (prep) drug for hiv prevention, under skin or into muscle
Injection of hiv prep drug
Related BillBusted guides
Plain-English reads if you see G9998 on a bill.
G9998 FAQ
Plain-English answers.
What is G9998 used for on a medical bill?
HCPCS code G9998 is used on medical bills for professional services (cms-defined procedures): 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]). Up to 49% of medical bills contain at least one error (CFPB, 2023), and codes in this category most often get flagged for service billed at a level not supported by documentation. If you see G9998 on your bill, request the itemized statement and compare the units, date of service, and description to your Explanation of Benefits before paying.
How much should G9998 cost?
How much G9998 should cost depends on your payer and region. Up to 49% of medical bills contain at least one error (CFPB, 2023), and pricing for this HCPCS code is set by Medicare fee schedules for Medicare claims and by negotiated allowed amounts for commercial plans. Check the Medicare fee-schedule lookup tool, your insurer's member portal, or run a free BillBusted scan to compare your charge against typical allowed amounts.
Can I dispute a G9998 charge on my medical bill?
Yes, you can dispute a G9998 charge on your medical bill if the units, modifier, date of service, or coverage doesn't match the medical record or your insurance benefits. About 73.7% of patients who actually dispute a medical bill receive a correction (JAMA Health Forum, 2024). Request the itemized bill, compare to your EOB, and use BillBusted's Resolution Pack to draft the dispute letter if needed.
Don't pay G9998 blindly.
The free scan tells you in under 60 seconds whether this charge looks reasonable for your situation.