A09 vs R19.7
A09 and R19.7 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 official note, declared on A09
diarrhea NOS (R19.7)
A09
Infectious gastroenteritis and colitis, unspecified
BillableUnspecified
- Chapter 1
- Certain infectious and parasitic diseases
- Section
- A00-A09
Use when the record says
- Infectious colitis NOS
- Infectious enteritis NOS
- Infectious gastroenteritis NOS
Indexed under
- 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)
R19.7
Diarrhea, unspecified
BillableUnspecified
- Chapter 18
- Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
- Section
- R10-R19
Use when the record says
- Diarrhea NOS
Indexed under
- Diarrhea, diarrheal (disease) (infantile) (inflammatory)
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