Excludes1 pair
Z42.1 vs Z44.3-
Z42.1 and Z44.3 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 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
- Encounter › breast reconstruction following mastectomy
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 (external)
- Fitting › artificial › breast
- Fitting › prosthesis › breast
- Admission › adjustment › breast › prosthesis (external)
- Admission › adjustment › prosthesis › breast
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