Final answer:
The nurse should first check the patient's vital signs, such as BP and pulse, to assess for urgent issues like hemorrhage or shock, which can cause dizziness and lightheadedness. Then, inspect the surgical dressing and assess the abdomen for further clues.
Step-by-step explanation:
The nurse caring for a patient who is 1 day postoperative for abdominal surgery and reports pain unrelieved by medication should first collect objective data on the patient's vital signs, such as blood pressure (BP) and pulse. These measurements will quickly indicate if there is an urgent concern, like hemorrhage or shock, which could align with the patient's symptoms of dizziness, lightheadedness, and nausea. In addition to these vital signs, checking the surgical dressing for any signs of blood or drainage and assessing the abdomen for distention and rigidity would be appropriate, followed by reviewing the patient’s hematocrit and hemoglobin levels to rule out anemia or ongoing bleeding.