A09 vs K52.9
A09 and K52.9 can never be reported together. ICD-10-CM declares them mutually exclusive with an Excludes1 note, meaning the two conditions cannot occur in the same patient — so exactly one of them is correct for any given encounter. The distinction is infectious vs non-infective origin.
Infectious gastroenteritis and colitis, unspecified
- Chapter 1
- Certain infectious and parasitic diseases
- Section
- A00-A09
- Infectious colitis NOS
- Infectious enteritis NOS
- Infectious gastroenteritis NOS
- Dysentery, dysenteric (catarrhal) (diarrhea) (epidemic) (hemorrhagic) (infectious) (sporadic) (tropical)
- Diarrhea, diarrheal › dysenteric (disease) (infantile) (inflammatory)
- Diarrhea, diarrheal › endemic (disease) (infantile) (inflammatory)
- Diarrhea, diarrheal › epidemic (disease) (infantile) (inflammatory)
- Diarrhea, diarrheal › infectious (disease) (infantile) (inflammatory)
Noninfective gastroenteritis and colitis, unspecified
- Chapter 11
- Diseases of the digestive system
- Section
- K50-K52
- Colitis NOS
- Enteritis NOS
- Gastroenteritis NOS
- Ileitis NOS
- Jejunitis NOS
- Sigmoiditis NOS
- Cecitis
- Colitis (acute) (catarrhal) (chronic) (noninfective) (hemorrhagic)
- Enteritis (acute) (diarrheal) (hemorrhagic) (noninfective)
- Enterocolitis
- Gastroenteritis (acute) (chronic) (noninfectious)
These two codes sit in different chapters of the Tabular List, which is usually the clearest signal that they describe different underlying processes rather than different degrees of the same one.
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027