Chapter 21 in ICD-10-CM contains our “Z” codes. Z codes (other reasons for healthcare encounters) may be assigned as appropriate to further explain the reasons for presenting for healthcare services, including transfers between healthcare facilities, or provide additional information relevant to a patient encounter. The ICD-10-CM Official Guidelines for Coding and Reporting identify which codes maybe assigned as principal or first-listed diagnosis only, secondary diagnosis only, or principal/first-listed or secondary (depending on the circumstances). Assign as many codes as necessary to fully explain each healthcare encounter. Since patient history information may be very limited, use any available documentation to assign the appropriate external cause of morbidity and Z codes.

Z codes are designated as the principal /first listed diagnosis in specific situations such as:

• To indicate that a person with a resolving disease, injury or chronic condition is being seen for specific aftercare, such as the removal of internal fixation devices. One example would be an encounter to remove orthopedic pins.
• To indicate that a person is seen for the sole purpose of special therapy, such as chemotherapy, immunotherapy and radiation therapy.
• To indicate that a person not currently ill is encountering the health service for a specific reason, such as to act as an organ donor, encounter for medical observation for suspected diseases and conditions ruled out, administrative examinations (pre-employment exam, recruitment to armed forces), plastic and reconstructive surgery following medical procedures or healed injury (breast reconstruction following mastectomy).
• To indicate the birth status of newborns

There are several categories of “Z” codes found in Chapter 21 and they include encounters for Contact/Exposure to communicable diseases, Inoculations and vaccinations, statuses, personal and family history, Surveillance/Screening, aftercare, follow-up, observation, organ donor, counseling, encounters for obstetric and reproductive services, newborns and infants, and routine/administrative exams. Individual facilities may have internal policies that differ on capturing of certain Z codes so make sure you review your facility’s policies. Here are a few tips for when to use certain categories of Z codes:

• Observation (Z03-Z05) The observation codes are generally used as a principal/first-listed diagnosis only but may be assigned as a secondary diagnosis code when the patient is being observed for a condition that is ruled out and is unrelated to the principal/first-listed diagnosis.
• Follow codes (Z08-Z09) These codes indicated for continued surveillance (treatment has been completed and disease, condition, or injury no longer exists.
• Screening/Surveillance codes (Z11-Z13) are used for Testing in healthy individuals so early detection and treatment can be provided and the patient has no sign or symptoms of the disease/condition.
• Aftercare codes (Z47-Z48) are used for patients receiving continued care in the healing phase or for the long-term consequences of a disease. Reminder: Do not use these codes with the injury codes, instead code to the specific injury with the 7^th character for subsequent encounter.
• Counseling Z codes are found throughout chapter 21 and are used when a patient or family member receives assistance in the aftermath of an illness or injury, or when support is required in coping with family or social problems