A 45-year-old male presents to the emergency department with sudden onset of severe, diffuse abdominal pain that started 6 hours ago. The pain is non-radiating and the patient describes it as a constant, sharp ache. His abdomen is diffusely tender on palpation but there is no rebound tenderness. Vital signs show a heart rate of 110 bpm, blood pressure of 145/90 mmHg, and temperature of 38.2°C (100.8°F). Laboratory results reveal elevated white blood cells. There are no signs of external trauma. Which of the following should be the most immediate next step in the management of this patient?
Administer broad-spectrum antibiotics.
Obtain abdominal X-ray.
Perform an immediate exploratory laparotomy.
Obtain an abdominal CT scan.