Final answer:
A urine output of 20 mL/hr is the finding that should be reported to the provider after a postoperative assessment following an appendectomy as it indicates potential renal issues.
Step-by-step explanation:
A nurse assessing a client who is 2 hr postoperative following an appendectomy should report a urine output of 20 mL/hr to the provider. This amount is considerably low, indicating possible inadequate renal perfusion or urinary retention, potentially necessitating further assessment and intervention. Other findings such as a body temperature of 36.5°C, a small area of bloody drainage on the dressing, and a WBC count of 9,000 mm³ are within normal ranges post-surgery and typically are not immediately concerning.