A client with renal calculi is experiencing hematuria and reports severe flank pain. Which intervention should the nurse implement first?

A. Administer a prescribed opioid analgesic: Severe flank pain caused by renal calculi can be excruciating and may trigger sympathetic nervous system responses such as hypertension and tachycardia, making pain management the first priority. B. Prepare the client for a prescribed computed tomography (CT) scan: A CT scan is important for diagnosing the location and size of the stone, but managing the client's acute pain takes precedence before diagnostic imaging. C. Obtain a urine specimen for analysis: Urine analysis is useful to check for infection, crystals, or blood, but collecting a specimen can be delayed slightly until after the client’s immediate pain is addressed. D. Strain the urine for the presence of stones: Straining urine helps identify stone type for treatment planning, but it is not as urgent as providing prompt relief of the client's severe and debilitating pain.