[Trans-sigmoid urinary diversion and dediversion and cancer: experimental study].

The present experimental study was carried out in 75 female Wistar rats. End-to-side vesicosigmoidostomy was performed in 65; the remaining 10 rats comprised the control group. Thirty-three rats were de-diverted at 1 and 2 months later. The site of the vesicosigmoid anastomosis was assessed histologically at 1, 2, and 3 months postoperatively in diverted rats, and at 1 and 2 months in de-diverted rats. Squamous metaplastic changes and variable degrees of transitional cell line neoplasm were observed in the diverted rats. Bladder changes did not regress significantly after de-diversion. No structural changes were observed at the level of the sigmoid. This experimental animal model confirms the oncogenic potential of mixing feces and urine, and shows that de-diversion does not achieve significant regression of bladder tumor lesions.