The nurse is assessing a client who has a history of kidney stones and returns to the clinic with flank pain. Which intervention should the nurse implement first?

Choice A reason: Observing nonverbal signs is helpful but subjective. It should complement, not replace, a structured pain assessment. Choice B reason: Using a standardized pain scale provides objective data on pain severity, guiding immediate management and further evaluation. It is the first step in pain assessment. Choice C reason: Urine collection and straining are diagnostic steps but should follow pain assessment and stabilization. Choice D reason: Asking about prior medication use is relevant but not the priority when initiating pain evaluation and management.