MSFinals-6653
A 67-year-old man is admitted to the colorectal ward after undergoing resection of a large adenocarcinoma in his descending colon. The surgery involved a left hemicolectomy and removal of two loops of small bowel and a partial cystectomy due to tumour invasion. He is currently five days post-operation and is managing well with adequate pain control. However, his catheter has drained 2000ml in the last 24 hours, and his abdominal surgical drain is still producing 200-300 ml of clear yellow fluid per day. There is a concern that his bladder wall repair may be leaking urine. What investigation should be ordered to provide the most definitive result in assessing the healing of the bladder suture line?