Pediatric Coding Alert

Question: I know that Z23 is the primary diagnosis code for immunizations, but does it get linked as a secondary diagnosis when the immunizations are connected to a well visit? Or do you just list Z00.12, given that “immunizations appropriate for age” is listed as a synonym for the well-child exam?

Maryland Subscriber

Answer: ICD-10 guideline C.21.c.2 notes that Z23 (Encounter for immunization) “may be used as a secondary code if the inoculation is given as a routine part of preventive health care, such as a well-baby visit.” This is confirmed by the instructional note that accompanies the code which tells you to “code first any routine childhood examination.”

So, you would not simply list Z00.12 (Encounter for routine child health examination) as the sole diagnosis even though, as you say, one of the code’s synonyms refers to age-appropriate immunizations. Instead, you would add Z23 as the secondary diagnosis to Z00.12 when applicable.

Don’t forget: The ICD-10 guideline also notes that “procedure codes are required to identify the actual administration of the injection and the type(s) of immunizations given.” This echoes the note that accompanies Z23 informing you that “procedure codes are required to identify the types of immunizations given.”