Answer: At first glance these codes look very similar, but heres the difference. The 99218-220 are used only to report encounter(s) by the supervising physician with a patient when designated or admitted under observation status to a hospital for not more than 24 hours but discharged on a different date of service. The discharge of this patient would be coded with the 99217 code for Observation Care Discharge. The 99234-236 codes are used for both observation and inpatient services provided on the same date of service. These codes include both the admission and discharge and would not allow you to use the 99217.