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ICD-10 Code A09: Infectious gastroenteritis and colitis, unspecified

A09 is a billable ICD-10 diagnosis code used to classify Infectious gastroenteritis and colitis, unspecified in medical records and claims. You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records. ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Certain infectious and parasitic diseases (A00-B99).

Reviewed by HealthAssure Clinical TeamUpdated 26 May 2026

What is this code?

ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Certain infectious and parasitic diseases (A00-B99).

When is it used?

  • May be used when a clinician documents infectious gastroenteritis and colitis, unspecified in a patient's medical record.
  • May appear in hospital records, claims, referrals, and clinical documentation.
  • This code can be used as a clinically usable diagnosis entry in standardized coding workflows.

What it does not mean

  • A code alone does not explain severity, treatment plan, or outcome.
  • A medical code should not be treated as a substitute for a doctor's diagnosis or advice.

Code hierarchy

chapter
1Certain infectious and parasitic diseases (A00-B99)
block
A00-A09Intestinal infectious diseases
currentA00-A09

Official coding notes

Inclusion terms
  • Infectious colitis NOS
  • Infectious enteritis NOS
  • Infectious gastroenteritis NOS
Excludes1 (do not code together)
  • colitis NOS (K52.9)
  • diarrhea NOS (R19.7)
  • enteritis NOS (K52.9)
  • gastroenteritis NOS (K52.9)
  • noninfective gastroenteritis and colitis, unspecified (K52.9)

Where you may see this code

You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records.

Related specialists

Infectious Disease SpecialistGeneral Physician

Coverage-related procedures and services

CPT 44388high
COLONOSCOPY THROUGH STOMA; DIAGNOSTIC, INCLUDING COLLECTION OF SPECIMEN(S) BY BRUSHING OR WASHING, WHEN PERFORMED (SEPARATE PROCEDURE)
Source: CMS coverage guidance
CPT 44401high
COLONOSCOPY THROUGH STOMA; WITH ABLATION OF TUMOR(S), POLYP(S), OR OTHER LESION(S) (INCLUDES PRE-AND POST-DILATION AND GUIDE WIRE PASSAGE, WHEN PERFORMED)
Source: CMS coverage guidance
CPT 44389high
COLONOSCOPY THROUGH STOMA; WITH BIOPSY, SINGLE OR MULTIPLE
Source: CMS coverage guidance
CPT 44391high
COLONOSCOPY THROUGH STOMA; WITH CONTROL OF BLEEDING, ANY METHOD
Source: CMS coverage guidance
CPT 44402high
COLONOSCOPY THROUGH STOMA; WITH ENDOSCOPIC STENT PLACEMENT (INCLUDING PRE- AND POST-DILATION AND GUIDE WIRE PASSAGE, WHEN PERFORMED)
Source: CMS coverage guidance
CPT 44390high
COLONOSCOPY THROUGH STOMA; WITH REMOVAL OF FOREIGN BODY(S)
Source: CMS coverage guidance

Coding guidelines

Compatibility

Legacy and official ICD code match exactly.
Legacy codes
A09

Common synonyms

Infectious gastroenteritis and colitis, unspecifiedInfectious gastroenteritis and colitis

Frequently asked questions

Code details

CodeA09
SystemICD10
Display nameInfectious gastroenteritis and colitis, unspecified
ChapterCertain infectious and parasitic diseases (A00-B99)
BlockIntestinal infectious diseases

Flags

BillableYes
Valid clinical useYes

Source

SourceICD-10
Version2026-annual
Releaseannual
Year2026

Index terms

Matched terms
Arthritis, arthritic(acute) (chronic) (nonpyogenic) (subacute)Colitis(acute) (catarrhal) (chronic) (noninfective) (hemorrhagic)Diarrhea, diarrheal(disease) (infantile) (inflammatory)Diarrhea, diarrheal(disease) (infantile) (inflammatory)Diarrhea, diarrheal(disease) (infantile) (inflammatory)Diarrhea, diarrheal(disease) (infantile) (inflammatory)Disease, diseasedDysentery, dysenteric(catarrhal) (diarrhea) (epidemic) (hemorrhagic) (infectious) (sporadic) (tropical)Dysentery, dysenteric(catarrhal) (diarrhea) (epidemic) (hemorrhagic) (infectious) (sporadic) (tropical)Enteritis(acute) (diarrheal) (hemorrhagic) (noninfective)Enteritis(acute) (diarrheal) (hemorrhagic) (noninfective)Enteritis(acute) (diarrheal) (hemorrhagic) (noninfective)
See also
category M01

About this content

This page is prepared by HealthAssure's clinical team using official coding standards from ICD-10. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.

ICD-10 Code A09 for Infectious gastroenteritis and colitis, unspecified | HealthAssure