Z42.1 vs Z44.3
Z42.1 and Z44.3 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 Z44.3
encounter for breast reconstruction following mastectomy (Z42.1)
Z42.1
Encounter for breast reconstruction following mastectomy
Billable
- Chapter 21
- Factors influencing health status and contact with health services
- Section
- Z40-Z53
Indexed under
- Admission › breast reconstruction following mastectomy (for)
- Encounter › breast reconstruction following mastectomy (with health service) (for)
Z44.3
Encounter for fitting and adjustment of external breast prosthesis
Not billable
- Chapter 21
- Factors influencing health status and contact with health services
- Section
- Z40-Z53
Indexed under
- Admission › fitting › breast prosthesis (for)
- Fitting › artificial › breast (and adjustment) (of)
- Fitting › prosthesis › breast (and adjustment) (of)
- Admission › adjustment › breast › prosthesis (for)
- Admission › adjustment › prosthesis › breast (for)
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