Final answer:
A history of asthma requires further assessment before undergoing a CT scan with an IV contrast agent.
Step-by-step explanation:
Among the options presented, the nurse should identify that the client's history of asthma requires further assessment before undergoing a CT scan with an IV contrast agent. Asthma is a chronic respiratory condition that can increase the risk of adverse reactions to contrast agents. Further assessment is needed to evaluate the severity of the asthma and determine if any precautions or modifications need to be made before the procedure.
The other options - appendectomy 1 year ago, penicillin allergy, and total knee arthroplasty 6 months ago - do not necessarily require further assessment before the CT scan. While past surgeries and allergies should always be noted, they do not directly impact the safety or appropriateness of a CT scan with IV contrast.