FY2027
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Excludes1 pair

P39.0 vs P83.4

P39.0 and P83.4 are not coded together. ICD-10-CM declares them mutually exclusive with an Excludes1 note — the two conditions are not expected to occur together, so exactly one of them is normally correct for a given encounter. The Official Guidelines carve out one exception: if the two conditions are clearly unrelated to each other, both may be reported.

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
  • Abscess › breast › newborn
  • Mastitis › infective › newborn
  • Mastitis › neonatal › infective
  • Newborn › mastitis › infective
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 (noninfective)
  • Newborn › breast engorgement
  • Engorgement › breast › newborn
  • Hypertrophy, hypertrophic › breast › newborn
  • Newborn › mastitis › noninfective

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