Use of ethylene vinyl alcohol copolymer for tubal sterilization by selective catheterization in rabbits

PURPOSE: To assess the efficacy of ethylene vinyl alcohol copolymer (Uryx) in nonsurgically occluding the fallopian tube and achieving tubal steriliza tion in the rabbit model. MATERIALS AND METHODS: Ten mature virgin female New England rabbits underwe nt transvaginal selective bilateral fallopian tube cannulation with use of a coaxial catheter system under general anesthesia. Selective salpingograph y was performed bilaterally to assess patency of the fallopian tubes. Ethyl ene vinyl alcohol copolymer was injected unilaterally through a microcathet er to completely fill the middle portion of the tube. Three to seven days a fter injection, each animal was bred. Conception was determined by ultrason ography (US) 7-19 days after effective breeding. If pregnant, the rabbit wa s killed. Otherwise, it was permitted to rebreed until pregnancy was achiev ed. Histologic specimens of the fallopian tubes were prepared and analyzed. RESULTS: Patency of the fallopian tubes was demonstrated bilaterally in all animals by the free spillage of contrast material into the peritoneum. The delivery of ethylene vinyl alcohol copolymer into the fallopian tubes was successful in all animals but one, in which most of the plug almost immedia tely extruded into the uterus. Pregnancy was detected by US in the untreate d fallopian tube in the nine rabbits that were receptive to breeding. No pr egnancies were detected in the injected side. Histologic analysis demonstra ted variable degrees of occlusion, fibrosis, and inflammation, with the maj ority of specimens demonstrating mild to moderate inflammation and moderate to marked fibrosis. CONCLUSION: Ethylene vinyl alcohol copolymer can reliably be placed nonsurg ically via the transvaginal approach into the fallopian tubes with use of a coaxial catheter system. Ethylene vinyl alcohol copolymer appears to resul t in less fibrosis than previously investigated agents and demonstrates a 1 00% early sterilization rate in the rabbit model.