K65 vs P78.1
K65 and P78.1 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 K65
neonatal peritonitis (P78.0-P78.1)
P78.1
Other neonatal peritonitis
Billable
- Chapter 16
- Certain conditions originating in the perinatal period
- Section
- P76-P78
Use when the record says
- Neonatal peritonitis NOS
Indexed under
- Peritonitis › congenital (adhesive) (bacterial) (fibrinous) (hemorrhagic) (idiopathic) (localized) (perforative) (primary) (with adhesions) (with effusion)
- Peritonitis › neonatal (adhesive) (bacterial) (fibrinous) (hemorrhagic) (idiopathic) (localized) (perforative) (primary) (with adhesions) (with effusion)
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