A09 Infectious gastroenteritis and colitis, unspecified

✓ Billable ICD-10-CM 2026
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The ICD-10-CM code for Infectious gastroenteritis and colitis, unspecified is A09 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Section
A00-A09: Intestinal infectious diseases (A00-A09)
Category A09
1 code (1 billable)
FY2026 Status
Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to A09:

  • Dysentery, dysenteric (catarrhal) (diarrhea) (epidemic) (hemorrhagic) (infectious) (sporadic) (tropical)
  • Diarrhea, diarrheal (disease) (infantile) (inflammatory) › epidemic
  • Enteritis (acute) (diarrheal) (hemorrhagic) (noninfective) › epidemic (infectious)
  • Disease, diseased › diarrheal, infectious NEC
  • Diarrhea, diarrheal (disease) (infantile) (inflammatory) › dysenteric
  • Diarrhea, diarrheal (disease) (infantile) (inflammatory) › endemic
  • Dysentery, dysenteric (catarrhal) (diarrhea) (epidemic) (hemorrhagic) (infectious) (sporadic) (tropical) › arthritis
  • Diarrhea, diarrheal (disease) (infantile) (inflammatory) › infectious
Excludes1
Not coded here. These conditions should NOT be coded together with A09.
  • colitis NOS (K52.9)
  • diarrhea NOS (R19.7)
  • enteritis NOS (K52.9)
  • gastroenteritis NOS (K52.9)
  • noninfective gastroenteritis and colitis, unspecified (K52.9)

Inclusion Terms

  • Infectious colitis NOS
  • Infectious enteritis NOS
  • Infectious gastroenteritis NOS

U.S. Hospital Utilization

  • An estimated 58,745 U.S. inpatient stays in 2023 included A09 among the documented diagnoses.
  • 19,940 stays listed it as the principal diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

HIV Infections (TOC entry)

a. Human Immunodeficiency Virus (HIV) Infections .............................................................. 19

— ICD-10-CM Official Guidelines for Coding and Reporting, FY2026, Section I.C.1.a
Infectious agents causing diseases in other chapters (TOC)

b. Infectious agents as the cause of diseases classified to other chapters ................................. 22

— ICD-10-CM Official Guidelines for Coding and Reporting, FY2026, Section I.C.1.b

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

Search all 70,000+ ICD-10-CM codes →
Reviewed by Prajwal Shrestha, CPC, CRC
Certified Professional Coder (CPC) and Certified Risk Adjustment Coder (CRC) · AAPC Member ID 01997614 · About · Editorial policy · Content last reviewed: 2025-10-01

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