EVALUATION OF POLYDIMETHYLSILOXANE AS AN ALTERNATIVE IN THE ENDOSCOPIC TREATMENT OF VESICOURETERAL REFLUX

Endoscopic correction of vesicoureteral reflux is an attractive altern ative to open repair. In terms of effectiveness and long-term successf ul results polytetrafluoroethylene (Polytef) is the most reliable inje ctable product. However, legitimate concerns regarding particle migrat ion still exist for polytetrafluoroethylene. Polydimethyl siloxane (Ma croplastique) was evaluated as an alternative to polytetrafluoroethyle ne. Seven mongrel female dogs underwent endoscopic suburothelial injec tions of 0.35 to 0.50 cc polydimethylsiloxane paste by the O'Donnell t echnique to a unilateral nonrefluxing ureteral orifice. To facilitate migratory surveillance the paste was mixed with (57)carbon monoxide ra diolabeled 80 mu m. microspheres and injected in 5 of the 7 animals. A nimals were sacrificed at 1, 3 and 6-month intervals. All major organs were retrieved and processed. After intensive histological evaluation the remaining tissue underwent dissolution and centrifugation in sodi um hypochlorite. The resulting insoluble pellet was further analyzed. In dogs injected with radiolabeled paste tissue samples and insoluble pellets of each organ system were analyzed for gamma counts. Smears of the insoluble pellets of all animals were examined on light and phase contrast microscopy. At autopsy no gross abnormalities were noted. Ti ssue reaction at injection sites revealed a well encapsulated foreign body reaction with predominantly giant cells, fibroblasts and collagen deposition. Limited local migration of polydimethylsiloxane particles into the periureteral lymphatics of 1 animal sacrificed at 1 month wa s noted and a single particle visually indistinguishable from polydime thylsiloxane also was found within the splenic capsule. The endoscopic procedure in this animal was complicated in that 2 separate injection s were required and histological evaluation confirmed that the injecti ons were performed uniquely deep into the bladder muscularis. Radioact ive counts and dissolution of all major organ systems demonstrated no migration in the remaining 6 animals. Endoscopic subureteral injection of polydimethylsiloxane is technically feasible, and it may prove to be biocompatible and without risk of distant migration if injected cor rectly.