A 52-year-old woman undergoes a sigmoid resection with primary anastomosis for recurrent diveiculitis. She returns to the emergency room 10 days later with left flank pain and decreased urine output; laboratory examination is significant for a white blood cell (WBC) count of 20,000/mm3 . She undergoes a CT scan that demonstrates new left hydronephrosis, but no evidence of an intraabdominal abscess. Which of the following is the most appropriate next step in management?
Intravenous pyelogram Intravenous antibiotics and repeat CT in 1 week Administration of intravenous methylene blue No fuher management if urinalysis is negative for hematuria