Patients receiving therapeutic services only For patients receiving therapeutic services only during an encounter/visit, sequence first the diagnosis, condition, problem, or other reason for encounter/visit shown in the medical record to be chiefly responsible for the outpatient services provided during the encounter/visit. Codes for other diagnoses (e.g., chronic conditions) may be sequenced as additional diagnoses.

The only exception to this rule is that when the primary reason for the admission/encounter is chemotherapy or radiation therapy, the appropriate Z code for the service is listed first, and the diagnosis or problem for which the service is being performed listed second.