Uretersigmoidostomy in the adult has progressively been abandoned because of its high complication rate (both metabolic and functional). We have studied the feasibility of a new model of ureterorectal diversion in 12 Beagle dogs, with the aim of increasing rectal capacity and decreasing rectal pressure. A segment of the ileum was isolated and opened along its antimesenteric border to obtain a patch into which the right ureter was implanted, the left ureter being left intact to allow comparison of the kidneys postoperatively. The patch was then sutured to the edges of a large anterior rectotomy. Modifications of rectal physiology were studied by recording the rectal pressure after distension by a latex balloon both preoperatively and 3 months postoperatively, so that it was possible to evaluate the elasticity of the rectal wall. Radiographic studies and examination of autopsy specimens after 3 months yielded the impression of a reservoir added to the rectal space. Intrarectal pressure was significantly decreased (50% of the preoperative value) for a given distension volume following rectal augmentation (P less than 0.01). The elasticity of the rectal wall was not modified but the capacity of the reservoir was increased. The ureteroileal implantation was patent in two of the five evaluable dogs out of seven implantations performed. In these cases, signs of pyelonephritis were found in the right kidneys. In the remaining cases the implantation became obstructed for reasons mainly related to canine anatomy and experimental conditions. These technical difficulties in the dog make it impossible to assess the quality of this reimplantation technique in this model.(ABSTRACT TRUNCATED AT 250 WORDS)