N65 vs Z42.1
N65 and Z42.1 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.
Deformity and disproportion of reconstructed breast
- Chapter 14
- Diseases of the genitourinary system
- Section
- N60-N65
Encounter for breast reconstruction following mastectomy
- Chapter 21
- Factors influencing health status and contact with health services
- Section
- Z40-Z53
- Admission › breast reconstruction following mastectomy (for)
- Encounter › breast reconstruction following mastectomy (with health service) (for)
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