Experimental nonsurgical female sterilization: transcervical implantation of microspindles in fallopian tubes

Abstract

Purpose: A nonsurgical method of female sterilization was investigated in rabbits.

Materials and methods: A self-expanding microspindle (length 9-18 mm, diameter 1.5-2.0 mm) made from tubular metal mesh was implanted in a single fallopian tube of 12 rabbits via catheterization of a single uterus. The contralateral fallopian tube and uterus served as controls. Each rabbit was scheduled to undergo three cycles of breeding. Before delivery, absence of pregnancy on the side with the microspindle was verified with hysterography.

Results: Eight rabbits completed three cycles of breeding and pregnancy. Two rabbits had one pregnancy. Two rabbits did not conceive. Spindles were placed correctly in 11 rabbits. Successful contraception was achieved in nine rabbits, who had 25 gestations on the nonspindle side and no gestation on the spindle side. One rabbit, which received the shortest spindle, was bilaterally pregnant, indicating a failure of contraception on the spindle side. No spindles dislocated. Histologic study showed all spindles firmly embedded in the tubal wall without signs of inflammation.

Conclusion: Microspindles of a certain minimum length have potential as a transcervically implantable, permanent intratubal contraceptive device.

PIP: A simple, nonsurgical female sterilization method involving fallopian tube catheterization under fluoroscopic guidance and implantation of microspindles was investigated in laboratory animals. A self-expanding microspindle made from tubular metal mesh was implanted in a single fallopian tube of 12 New Zealand Cross rabbits through catheterization of a single uterus. The contralateral fallopian tube and uterus served as controls. 8 rabbits completed three cycles of breeding and pregnancy; 2 rabbits had one pregnancy and 2 rabbits did not conceive (one presumably because of incorrect spindle placement). Successful contraception was achieved in 9 rabbits, who had 25 gestations on the nonspindle side and none on the spindle side. The rabbit with bilateral pregnancy (the recipient of the shortest spindle) represents one contraceptive failure in a total of 26 valid cycles. At autopsy, all spindles were firmly embedded in the tubal wall with no signs of inflammation. Complete obstruction of the interior space of the spindle was absent in all cases, indicating that complete occlusion of the tubal lumen was not the mechanism of action. A more likely explanation for the contraceptive effect observed in this study is the impairment of contractility of the spindle-carrying segment of the fallopian tube. These findings suggest that microspindles of a certain minimum length merit further investigation as a transcervically implantable, permanent intratubal contraceptive device.