Ureteroenteric strictures following retrosigmoid vs. conventional ileal conduit – The MOSAIC study (The DaBlaCa‐16 study)

To evaluate the rate of left-sided ureteroenteric strictures (UES) following robot-assisted radical cystectomy (RARC) with a retrosigmoid ileal conduit compared to a conventional ileal conduit in a randomised controlled trial (RCT). This multicentre, RCT included 303 patients undergoing RARC between May 2020 and August 2022. Patients were randomised to receive either a retrosigmoid or a conventional ileal conduit. Analyses were performed an intention-to-treat basis. Of the 149 patients randomised for the retrosigmoid ileal conduit, a total of 137 (92%) patients received the allocated conduit. In the control group, 150 of 154 (97.4%) patients underwent RARC and one patient was lost to follow-up. At a median follow-up of 754 days, the rate of left-sided UES was 4.1% (six of 148) in the intervention group and 6.7% (10 of 149) in the control group (P = 0.31). No significant differences were observed in postoperative creatinine clearance or metabolic complications, including vitamin B12 deficiency and metabolic acidosis. The rate of left-sided UES was not significantly reduced with the retrosigmoid conduit compared to the conventional approach. However, the procedure was feasible without increased risk of metabolic complications and therefore may be a good alternative when extensive resection of the left ureter is needed.