Submucosal injection of polyvinyl alcohol foam in rabbit bladder

Submucosal injection of either polytetrafluoroethylene (Teflon) or collagen has been used in the treatment of vesicoureteral reflux. Although the methods and principles of this treatment are effective, there are concerns regarding the safety and long-term effectiveness of these substances. We present a pilot study to explore the potential of an alternate substance (polyvinyl alcohol foam) for this treatment. Polyvinyl alcohol foam (Ivalon) particles measuring 150 to 250 mu. were injected submucosally into the bladder of New Zealand white rabbits. The bladder was examined macroscopically and microscopically at 1 and 2 weeks, and 1, 2 and 3 months after the injection. The particles created a raised lesion under the mucosa that was visible to the naked eye as late as 3 months after the submucosal injection. The particles remained in a submucosal location after 3 months. At 1 week after injection there was a foreign body giant cell response to the particles. At 3 months the giant cell response persisted and the particles were surrounded by a fibrotic reaction. There was little inflammatory response otherwise. These preliminary results indicate that polyvinyl alcohol foam may be suitable for subureteral injection in the treatment of vesicoureteral reflux.