K58.0 vs K59.1
K58.0 and K59.1 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 K59.1
irritable bowel syndrome with diarrhea (K58.0)
K58.0
Irritable bowel syndrome with diarrhea
Billable
- Chapter 11
- Diseases of the digestive system
- Section
- K55-K64
Indexed under
- Colic › mucous › with diarrhea (bilious) (infantile) (intestinal) (recurrent) (spasmodic)
- Colitis › spastic › with diarrhea (acute) (catarrhal) (chronic) (noninfective) (hemorrhagic)
- Irritable, irritability › colon › with diarrhea
- Spasm, spastic, spasticity › colon › with diarrhea (s)
- Irritable, irritability › bowel › with › diarrhea
K59.1
Functional diarrhea
Billable
- Chapter 11
- Diseases of the digestive system
- Section
- K55-K64
Indexed under
- Diarrhea, diarrheal › functional (disease) (infantile) (inflammatory)
- Diarrhea, diarrheal › neurogenic (disease) (infantile) (inflammatory)
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