A09 Infectious gastroenteritis and colitis, unspecified

Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.

Applicable to

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

Excludes1 (never 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)

Applies from A09 Infectious gastroenteritis and colitis, unspecified

Applicable to

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

Excludes1 (never 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)

MS-DRG index

Defines the logic of DRG(s) 391-392 in MDC 06.

Approximate ICD-9-CM (GEMs)

• 009.0 Infectious colitis, enteritis, and gastroenteritis (approximate)

Code annotations containing back-references to A09

Back-references to A09

• Type 1 Excludes: K52.9 Noninfective gastroenteritis and colitis, unspecified ("infectious gastroenteritis and colitis NOS (A09)")
• Type 2 Excludes: P37 Other congenital infectious and parasitic diseases ("infectious neonatal diarrhea (A00-A09)")

Back-references to A09

• Type 1 Excludes: K52.9 Noninfective gastroenteritis and colitis, unspecified ("infectious gastroenteritis and colitis NOS (A09)")
• Type 2 Excludes: P37 Other congenital infectious and parasitic diseases ("infectious neonatal diarrhea (A00-A09)")

Diagnosis Index entries for A09

• Arthritis, arthritic (acute) (chronic) (nonpyogenic) (subacute) › in (due to) › enteritis, infectious NEC
• Colitis (acute) (catarrhal) (chronic) (noninfective) (hemorrhagic) › regional › infectious
• Diarrhea, diarrheal (disease) (infantile) (inflammatory) › dysenteric
• Diarrhea, diarrheal (disease) (infantile) (inflammatory) › endemic
• Diarrhea, diarrheal (disease) (infantile) (inflammatory) › epidemic
• Diarrhea, diarrheal (disease) (infantile) (inflammatory) › infectious
• Disease, diseased › diarrheal, infectious NEC
• Dysentery, dysenteric (catarrhal) (diarrhea) (epidemic) (hemorrhagic) (infectious) (sporadic) (tropical)
• Dysentery, dysenteric (catarrhal) (diarrhea) (epidemic) (hemorrhagic) (infectious) (sporadic) (tropical) › arthritis
• Enteritis (acute) (diarrheal) (hemorrhagic) (noninfective) › epidemic (infectious)
• Enteritis (acute) (diarrheal) (hemorrhagic) (noninfective) › infectious NOS
• Enteritis (acute) (diarrheal) (hemorrhagic) (noninfective) › septic
• Enterocolitis › infectious NEC
• Gastroenteritis (acute) (chronic) (noninfectious) › epidemic (infectious)
• Gastroenteropathy › infectious
• Ileitis (chronic) (noninfectious) › infectious
• Ileocolitis › infectious
• Sigmoiditis › infectious
• Ulcer, ulcerated, ulcerating, ulceration, ulcerative › dysenteric

Nearby codes

• A09 Infectious gastroenteritis and colitis, unspecified (this code)