A nurse is caring for a patient who reports severe flank pain, nausea, and vomiting for 24 hours. Which of the following actions is the nurse's first priority?

Choice A reason: Administering pain medication is the first priority because severe flank pain can indicate renal colic, often caused by kidney stones. Pain management is essential to stabilize the patient, reduce sympathetic overdrive, and allow for further assessment and interventions. Uncontrolled pain can lead to increased blood pressure, tachycardia, and impaired respiratory effort, making it a critical first step. Choice B reason: Monitoring intake and output is important for evaluating renal function and hydration status, but it is not the immediate priority. It is a secondary intervention once the patient is stabilized and pain is controlled. Choice C reason: Straining the urine helps identify the presence of calculi and guide treatment, but it is not urgent compared to managing acute pain. It becomes relevant after initial stabilization. Choice D reason: Administering an antiemetic can improve comfort but does not address the primary issue of severe pain. It is supportive care and should follow analgesic administration.