P39.0 vs P83.4
P39.0 and P83.4 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 P39.0
breast engorgement of newborn (P83.4)
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)
P83.4
Breast engorgement of newborn
Billable
- Chapter 16
- Certain conditions originating in the perinatal period
- Section
- P80-P83
Use when the record says
- Noninfective mastitis of newborn
Indexed under
- Mastitis › neonatal (acute) (diffuse) (nonpuerperal) (subacute)
- Newborn › breast engorgement (infant) (liveborn) (singleton)
- Engorgement › breast › newborn
- Hypertrophy, hypertrophic › breast › newborn
- Newborn › mastitis › noninfective (infant) (liveborn) (singleton)
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