Does technique or material used affect bladder tissue reactions when injecting teflon or silicone paste?

Submucosal injections of polytetrafluoroethylene (PTFE) and polydimethylsiloxane (PDMS) paste continue to be used for the correction of vesicoureteral reflux and urinary incontinence. Potential distant particle migration and foreign body tissue reactions are thought to be significantly affected by the technique of injection and the paste material used. A study to determine if injection technique, paste material, or pretreatment of the injection site significantly affects local tissue reaction was performed on 44 New Zealand white rabbits.

Animals were randomly assigned to undergo four distinct injection treatments into the submucosa or bladder muscularis. Prior to injecting 0.1 cc of the PTFE or PDMS paste, some sites were pretreated with 0.1 cc saline to separate tissue planes, epinephrine to cause vasoconstriction, or doxycycline to provide sclerosis. Pretreatment controls were also performed without injecting PTFE or PDMS paste. Animals were killed, and quadrant bladder biopsies were performed at 1 hour (9), 1 day (9), 7 days (10), 1 month (8), and 6 months (8). A single pathologist, blinded to the injection treatments, performed a histologic evaluation to determine bleb location and the degree of inflammation, fibrosis, and epithelial necrosis.

Seven of the 12 submucosal PTFE injection treatments were found on biopsy to be primarily within the muscularis, compared to 1 of 9 with PDMS paste. Three of the 24 PTFE injections could not be found at autopsy. Of these, two were injected into the muscularis, and all were discovered at least 1 month following injection. Particles were present in all 22 PDMS injection sites that were retrieved. Pretreatments, especially with doxycycline, resulted in significant epithelial necrosis at 1 and 7 days. At 1 and 6 months there were no differences in inflammation or fibrosis between PTFE and PDMS or any pretreatment combinations with saline or epinephrine.

Correctly injected, silicone (PDMS) paste appears most likely to remain in the submucosal space. Pretreatment injections may cause early epithelial necrosis. PTFE and PDMS elicit similar foreign body reactions over time.