Progressive dilation for bladder tissue expansion.

Abstract

PURPOSE: The use of gastrointestinal tissue for augmentation cystoplasty is associated with numerous complications. We previously reported the development of a system in which ureters were progressively dilated and used for ureterocystoplasty. We have now applied a similar system for the progressive expansion of native bladder tissue. We investigated whether the expanded bladder tissue retained normal functional and phenotypic characteristics. MATERIALS AND METHODS: Urodynamic studies were performed in 5 beagle dogs and the bladder was divided horizontally into a superior bladder neo-reservoir, and an intact smaller bladder inferiorly with both ureters left intact and draining. A silicone catheter was threaded into the newly formed, superiorly located neo-reservoir, and connected to an injection port which was secured subcutaneously. A saline antibiotic solution was injected daily into the palpable injection port 4 weeks after surgery, dilating the neo-reservoir through the silicone catheter. Baseline and weekly cystograms were performed. Urodynamic studies of the neo-reservoirs were done immediately before sacrifice. Animals were sacrificed 3 months after the initial intervention and the bladder was examined grossly and microscopically. RESULTS: Within 30 days after progressive dilation, the neo-reservoir volume was expanded at least 10-fold according to radiography and cystometrograms. Urodynamic studies of the dilated neo-reservoirs showed normal compliance in all animals. Microscopic examination of the expanded neo-reservoir tissue revealed normal histology. A series of immunocytochemical studies demonstrated that the dilated bladder tissue maintained normal phenotypic characteristics. CONCLUSIONS: The system of progressive dilation is effective in expanding bladder tissue which is able to retain normal phenotypic and functional characteristics.