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Z42.1

Z42.1Encounter for breast reconstruction following mastectomy

Billable / specific codeICD-10-CMPOA exempt

Z42.1 is a billable, specific ICD-10-CM code for encounter for breast reconstruction following mastectomy. It is valid for submission on a claim.

Excludes1 — never code together

These conditions cannot occur together. Billing both on the same encounter is a denial.

  • deformity and disproportion of reconstructed breast (N65.1-)

Other codes that can never be billed with Z42.1

These codes carry an Excludes1 note pointing at Z42.1. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading Z42.1 alone.

  • Z41.1Encounter for cosmetic surgery
  • Z44.3Encounter for fitting and adjustment of external breast prosthesis
  • Z45.81Encounter for adjustment or removal of breast implant

Risk adjustment

Z42.1 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.

Medicare coverage

Z42.1 is named in 8 Medicare coverage policies 8 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.

  • A56587Billing and Coding: Cosmetic and Reconstructive Surgery
  • A56587Billing and Coding: Cosmetic and Reconstructive Surgery
  • A56658Billing and Coding: Cosmetic and Reconstructive Surgery
  • A57221Billing and Coding: Plastic Surgery

How Z42.1 is indexed

Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to Z42.1.

  • Admissionbreast reconstruction following mastectomy
  • Encounterbreast reconstruction following mastectomy

Related codes at this level

Codes that share Z42. If Z42.1 is not quite right, the correct code is usually one of these.

Questions about Z42.1

Is Z42.1 a billable ICD-10-CM code?
Yes. Z42.1 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
Where does Z42.1 sit in the tabular list?
Factors influencing health status and contact with health services (Z00-Z99), in the block Encounters for other specific health care (Z40-Z53).
What cannot be coded together with Z42.1?
Z42.1 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.
ICD-10-CMFY2026-Apr· effective April 1, 2026

Loaded directly from the CMS/NCHS ICD-10-CM public-domain release — see data sources and our editorial policy. If this page disagrees with the CMS tabular list, this page is wrong. Reference information for professional coders; not medical or billing advice.