Fallopian tube occlusion with a shape memory polymer device: evaluation in a rabbit model

BackgroundThe present study evaluates the feasibility of a shape memory polymer (SMP) device for fallopian tube occlusion in rabbits.Study designThe SMP contraceptive device is made of poly(dl-lactic acid)-based poly(urethane urea) SMP in the shape of a spiral cylinder that was 10 mm long and had a diameter of 2.6 mm. Using this device, bilateral transuterine fallopian tube occlusions were performed in 78 New Zealand white female rabbits. Forty-eight female rabbits (Group 1) were chosen as the experimental group and were implanted with the SMP devices. The remaining 30 female rabbits (Group 2) served as the control group, which only received an incision in the abdomen but no SMP device. Follow-up consisted of hysterosalpingography, histologic evaluation and contraceptive effect. In addition, the shape memory behavior and in vivo degradation characterization of the SMP device were observed in this study.ResultsUnder heat (37°C) stimulation, the temporary shape SMP device returned to its permanent shape within 60 s. The average weight loss percentage of SMP devices was 7.0% at 2 weeks and 72.5% at 12 weeks. The inflammatory reactions caused by SMP devices were aseptic and nonspecific at 2 and 12 weeks, respectively. The SMP device boundaries and the surrounding tissues were obscured by fiber hyperplasia in 11/12 tubes at 24 weeks. Hysterosalpingography showed an occluded fallopian tube of Group 1 in 6/6 rabbits at 12 weeks and 6/6 rabbits at 24 weeks. No pregnancy was found in all 18 rabbits of Group 1 (contraceptive rate of 100%); all 20 rabbits in the control group were pregnant.ConclusionBiodegradable and biocompatible SMP devices could provide reliable, instant and permanent tubal occlusion.