A04.9
BillableBacterial intestinal infection, unspecified
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is A04.9 an HCC code?
No. A04.9 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
A04.9 is the ICD-10-CM diagnosis code for bacterial intestinal infection, unspecified. A bacterial infection of the intestines where the specific type of bacteria causing the infection has not been identified or documented. This condition causes inflammation and irritation of the digestive tract, leading to symptoms like diarrhea, abdominal pain, and nausea. A04.9 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering intestinal infectious diseases (a00-a09).
A04.9 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
Use this code only when the specific bacterial organism cannot be determined; if the causative bacteria is identified (such as E. coli, Salmonella, or Shigella), use the more specific A04 subcategory codes instead.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for A04.9 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only when the specific bacterial organism cannot be determined; if the causative bacteria is identified (such as E. coli, Salmonella, or Shigella), use the more specific A04 subcategory codes instead
- •Document any associated symptoms like diarrhea (A09), dehydration, or electrolyte imbalances as secondary diagnoses to provide a complete clinical picture