Modified ureterosigmoidostomy (Mainz Pouch II): a nonrefluxing stented vs unstented laparoscopic porcine model

To describe a rapid and reproducible pure laparoscopic cystectomy and nonrefluxing modified continent urinary diversion (Mainz Pouch II), and to determine whether ureteric stenting decreases ureteric obstruction after surgery.

After institutional review and approval, six female pigs (51-55 kg) had a laparoscopic cystectomy and urinary diversion using a modified Mainz Pouch II. Imbricating bowel over the extra-intestinal ureteric segment created the nonrefluxing mechanism. All pigs had the same bowel preparation before a standard four-port transperitoneal laparoscopic procedure, but three pigs received bilateral J ureteric stents and three did not. Body weights, radiographic imaging, serum electrolytes and renal function were monitored during the 6-week survival period.

One stented pig developed bilateral pyelonephritis, renal obstruction and was killed. Including this pig, four of 12 renal units were obstructed, occurring more often in the stented pigs. There were no significant differences between the serum electrolytes before and after surgery or between the stented or unstented pigs. The surgery was quicker as experience increased. No pig developed hyperchloraemic metabolic acidosis. The nonrefluxing modification appeared to be effective, as reflux was only present in one renal unit.

Laparoscopic ureterosigmoidostomy, specifically the modified Mainz Pouch II, represents a viable and reasonable continent urinary diversion. The results suggest that there was no benefit in stenting in this pig model.