[Results of electron microscopy studies of the uterine horn of the New Zealand rabbit following use of 4 different coagulation methods].

The effect of 4 different coagulation methods used for sterilization, the subsequent process of wound healing, and the regeneration capability of tissue were investigated electron-microscopically. For that purpose, the uterus horns of white New Zealand rabbits were coagulated by monopolar or bipolar high frequency current or by endocoagulation through pelviscopy or by the CO2-laser through laparotomy. For each procedure coagulation power resp. temperature, coagulation time and interval from operation to tissue examination were varied. Monopolar and bipolar high frequency coagulation caused the largest zone of destruction, judged by the macroscopic, microscopic, and ultrastructural cell alterations. The nervus and blood vessels of the mesometrium were also subjected to coagulation effects. In endocoagulation, the destroyed area was limited to the tissue grasped by the crocodile forceps. The CO2-laser only produced a thin layer of coagulated tissue at the section edge. Altogether, only about 2-3 mm of tissue were destroyed. The small amount of tissue that had to be resorbed by inflammatory cells after endocoagulation allowed for a much more rapid healing process than after application of the two high frequency techniques. Characteristic of a healing process not completed even 5 months after monopolar high frequency coagulation, we saw carbonized necrotic remains and numerous macrophages and foreign body giant cells. Beginning or complete recanalization was found in 1/4 of the uterus horns operated by CO2-laser. An increased mitotic activity of undifferentiated cells indicated the attempts at complete reconstruction. The blastem-like tissue showed no differentiation towards ciliated or secretory epithelial cells yet. Endocoagulation should by preferred as the safer method for tubal sterilization because of the relatively small amount of tissue destruction, which, however, is sufficient for a complete separation of the uterus horns from the body, because the mesometrium is not damaged and because wound healing is quicker and adhesion formation is practically absent.