Evaluation of Polydimethylsiloxane as an Alternative in the Endoscopic Treatment of Vesicoureteral Reflux

Abstract

Endoscopic correction of vesicoureteral reflux is an attractive alternative to open repair. In terms of effectiveness and long-term successful results polytetrafluoroethylene (Polytef) is the most reliable injectable product. However, legitimate concerns regarding particle migration still exist for polytetrafluoroethylene. Polydimethylsiloxane (Macroplastique) was evaluated as an alternative to polytetrafluoroethylene. Seven mongrel female dogs underwent endoscopic suburothelial injections of 0.35 to 0.50 cc polydimethylsiloxane paste by the O'Donnell technique to a unilateral nonrefluxing ureteral orifice. To facilitate migratory surveillance the paste was mixed with 57carbon monoxide radiolabeled 80 microns. microspheres and injected in 5 of the 7 animals. Animals 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 sodium 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. Tissue 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 was noted and a single particle visually indistinguishable from polydimethylsiloxane also was found within the splenic capsule. The endoscopic procedure in this animal was complicated in that 2 separate injections were required and histological evaluation confirmed that the injections were performed uniquely deep into the bladder muscularis. Radioactive 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 correctly.

Recurrent Urinary Tract Infection by Bladder Stone Resulting from Subureteral Injection Polydimethylsiloxane (Macroplastique®) for Treatment of Vesicoureteral Reflux

“…Conversely, animal studies have reported formation of a well-encapsulated foreign body reaction at the administration site, composed of giant cells, fibroblasts, and collagen, with no substantial risk of migration [10]. Therefore, due to the risk of bladder mucosal necrosis, long-term follow-ups are required for patients who were administered PDS.…”

Biocompatibility of Injectable Microspheres

“…The irregular particles range from 16-400µm and 7 % are less than 50µm [71]. The lesser stimulatory effect of Macroplastique® on foreign body reactions in and around the urethra is certainly due to the highest immunological activity in in the skin compared to internal organs.…”

Endoscopic injection therapy for treatment of vesicoureteric reflux: A 20-year perspective

“…The take home message is that collagen is likely not as durable as polytef in terms of long term efficacy. However, it may provide a permanent (26). The initial reports on the results of Macroplastique STING came from Europe, and claimed 80% to 90% success after one injection (27,28).…”