Approach to a postoperative fever Quiz: Ace Your Exams

A 23-year-old man is postoperative day 7 following exploratory laparotomy for a gunshot wound to the abdomen which required small bowel resection and reanastomosis. He has been having persistent fevers and worsening abdominal pain for 4 days. His last bowel movement occurred on postoperative day 5 and he has not passed gas in 24 hours. He has no prior medical history. His current medications include IV morphine, IV ceftriaxone, and metronidazole. Temperature is 101.2°F (38.4°C), pulse is 112/minute, blood pressure is 125/82 mmHg, and respiratory rate is 22/minute. On physical examination, the patient appears to be in pain. Cardiopulmonary examination is normal. The abdomen is distended with decreased bowel sounds; there is no significant erythema, edema, or purulent drainage from the incision site. There is diffuse moderate tenderness to palpation, rebound, and guarding. White blood cell count is 18,500/mm³ (reference range: 4,500-11,000/mm³). Lab work also reveals low magnesium and potassium. Urinalysis and chest radiography are unremarkable. Blood and urine cultures are pending. Which of the following is the most appropriate next step in management?