FY2027
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Excludes1 pair

Z41.1 vs Z42.1

Z41.1 and Z42.1 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 Z41.1
encounter for post-mastectomy breast implantation (Z42.1)
Z41.1

Encounter for cosmetic surgery

Billable
Chapter 21
Factors influencing health status and contact with health services
Section
Z40-Z53
Use when the record says
  • Encounter for cosmetic breast implant
  • Encounter for cosmetic procedure
Indexed under
  • Admission › breast augmentation or reduction
  • Admission › cosmetic surgery NEC
  • Admission › plastic surgery, cosmetic NEC
  • Encounter › breast augmentation or reduction
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

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