Z codes that may only be principal/first-listed diagnosis

March 25, 2024 / By Courtney Crozier, RHIA, CCS

Whether you’re a seasoned coder or new to the industry, learning the coding guidelines and staying up to date with annual changes takes time and dedication. Each year presents new and exciting codes and often new guidelines, so it can be challenging to truly know it all. 

With the multitude of information available to coders, it’s easy to forget one of the simpler guidelines: Z codes that may only be principal/first-listed diagnosis. The guidelines have an entire section dedicated to the proper selection of the Principal Diagnosis (Section II. A-K), but for this blog post I’ll just touch on what the ICD-10-CM Official Guidelines for Coding and Reporting FY 2024 (Oct. 1, 2023 – Sept. 30, 2024) state about the Z codes and those that may only be principal/first-listed diagnosis. There are some exceptions to the rule, so make sure you brush up on this guideline.

The guidelines for the Z codes can be found under Section I.C.21.a-c. The specific section that outlines the Z codes that may only be coded as either principal or first listed diagnosis is found under Section I.C.21.c.16 which states:

The following Z codes/categories may only be reported as the principal/first-listed diagnosis, except when there are multiple encounters on the same day and the medical records for the encounters are combined:

  • Z00 Encounter for general examination without complaint, suspected or reported diagnosis Except: Z00.6
  • Z01 Encounter for other special examination without complaint, suspected or reported diagnosis Z02 Encounter for administrative examination
  • Z04 Encounter for examination and observation for other reasons
  • Z33.2 Encounter for elective termination of pregnancy
  • Z31.81 Encounter for male factor infertility in female patient
  • Z31.83 Encounter for assisted reproductive fertility procedure cycle
  • Z31.84 Encounter for fertility preservation procedure
  • Z34 Encounter for supervision of normal pregnancy
  • Z39 Encounter for maternal postpartum care and examination
  • Z38 Liveborn infants according to place of birth and type of delivery
  • Z40 Encounter for prophylactic surgery
  • Z42 Encounter for plastic and reconstructive surgery following medical procedure or healed injury
  • Z51.0 Encounter for antineoplastic radiation therapy
  • Z51.1- Encounter for antineoplastic chemotherapy and immunotherapy
  • Z52 Donors of organs and tissues Except: Z52.9, Donor of unspecified organ or tissue
  • Z76.1 Encounter for health supervision and care of foundling
  • Z76.2 Encounter for health supervision and care of other healthy infant and child
  • Z99.12 Encounter for respirator [ventilator] dependence during power failure

Whether you’ve been coding for three months or more than 30 years, keeping up to date with the coding guidelines is always a good rule of thumb.   

Courtney Crozier is a clinical development analyst 3M Health Information Systems.