| Z51 | Encounter for other aftercare and medical care | NON-BILLABLE CODE |
| Z51.0 | Encounter for antineoplastic radiation therapy | BILLABLE CODE |
| Z51.1 | Encounter for antineoplastic chemotherapy and immunotherapy | NON-BILLABLE CODE |
| Z51.11 | Encounter for antineoplastic chemotherapy | BILLABLE CODE |
| Z51.12 | Encounter for antineoplastic immunotherapy | BILLABLE CODE |
| Z51.6 | Encounter for desensitization to allergens | BILLABLE CODE |
| Z51.8 | Encounter for other specified aftercare | NON-BILLABLE CODE |
| Z51.81 | Encounter for therapeutic drug level monitoring | BILLABLE CODE |
| Z51.89 | Encounter for other specified aftercare | BILLABLE CODE |
