A Novel Technology for Reversible Fallopian Tubal Occlusion Using a Reverse Thermo-Responsive Polymer - Preliminary Results from a Rabbit Animal Study

Abstract Objectives : To determine if PF-88, a reverse thermo-responsive polymer designed to create a gel at body temperature and liquefy at a lower temperature (21o C) can reversibly occlude the fallopian tubes in rabbits. Study design : Mature female New Zealand White rabbits underwent laparotomy and placement of 22-gage catheter into the lumen of the distil uterine horns for evaluation of tubal patency by fluoroscopy using radio opaque contrast and treatment with PF-88. In the Acute Phase group (n =5) after PF-88 treatment we immediately cooled the serosal surface of the tube with ice for 90 seconds to liquify the gel then reassessed patency. In the Survival Phase groups, animals recovered from the initial surgery and then underwent a second procedure for evaluation of tubal occlusion and reversibility at 4 (n=3), 14 (n=2), and 28 (n=3) weeks after the initial procedure. We compared the histologic appearance of the treated fallopian tubes to untreated controls (n=3). Results : In the Acute Phase, we found all 10 fallopian tubes patent on initial evaluation, occluded following treatment with PF88, and patent following re-liquification by chilling. Animals in the Survival Group, all but one of the treated tubes appeared blocked at follow-up and patent following chilling. The treatment failure occurred in an animal in the 4-week group. Tubes treated with PF88 showed no histologic evidence of residual material or damage after removal of the polymer. Conclusion : The PF-88 reverse thermo-responsive polymer demonstrated the ability to reversibly block fallopian tubes for up to 28 weeks.