Excludes1 pair

B97.4 vs J21.0

B97.4 and J21.0 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 B97.4
acute bronchiolitis due to respiratory syncytial virus (RSV) (J21.0)
B97.4

Respiratory syncytial virus as the cause of diseases classified elsewhere

Billable
Chapter 1
Certain infectious and parasitic diseases
Section
B95-B97
Use when the record says
  • RSV as the cause of diseases classified elsewhere
Indexed under
  • Respiratory › syncytial virus, as cause of disease classified elsewhere
  • Virus, viral › respiratory syncytial › as cause of disease classified elsewhere
  • Virus, viral › respiratory syncytial › otitis media
  • Virus, viral › respiratory syncytial › upper respiratory infection
  • Infection, infected, infective › virus, viral NOS › respiratory syncytial › as cause of disease classified elsewhere
J21.0

Acute bronchiolitis due to respiratory syncytial virus

Billable
Chapter 10
Diseases of the respiratory system
Section
J20-J22
Use when the record says
  • Acute bronchiolitis due to RSV
Indexed under
  • Bronchiolitis › due to › respiratory syncytial virus (RSV)
  • Virus, viral › respiratory syncytial › bronchiolitis
  • Infection, infected, infective › virus, viral NOS › respiratory syncytial › bronchiolitis

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