N61 vs P39.0
N61 and P39.0 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 N61
neonatal infective mastitis (P39.0)
N61
Inflammatory disorders of breast
Not billable
- Chapter 14
- Diseases of the genitourinary system
- Section
- N60-N65
P39.0
Neonatal infective mastitis
Billable
- Chapter 16
- Certain conditions originating in the perinatal period
- Section
- P35-P39
Indexed under
- Newborn › mastitis (infant) (liveborn) (singleton)
- Abscess › breast › newborn (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
- Mastitis › infective › newborn (acute) (diffuse) (nonpuerperal) (subacute)
- Mastitis › neonatal › infective (acute) (diffuse) (nonpuerperal) (subacute)
- Newborn › mastitis › infective (infant) (liveborn) (singleton)
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