How to code 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.

Coding Examples

Patient had an outpatient phlebotomy performed for polycythemia vera.
ICD 10 code ; D45 polycythemia vera.

Female patient received outpatient chemotherapy for breast cancer with metastasis to the axillary lymph nodes.
ICD 10 code ; Z51.11 encounter for chemotherapy, C50.919 breast cancer, and C77.3 metastasis to axillary lymph nodes.

Patient had monthly B12 shot for pernicious anemia.
ICD 10 code ; D51.0 pernicious anemia, congenital.