Role of pronase hatching in enhancing the effectiveness of assisted reproductive technology programs

Background. Hatching from the zona pellucida is one of the most important stages of human preimplantation embryo development and spontaneous hatching inability is one of the causes of implantation failure in assisted reproductive technology (ART) cycles. The use of mechanical integrity disorders or complete destruction of the zona pellucida (assisted hatching) can be an effective way to enhance the effectiveness of infertility treatment programs using ART techniques. Objective. To assess the results of ART programs depending on the performance and type of assisted hatching. Material and methods. The prospective cohort investigation enrolled 309 patients treated for infertility with in vitro fertilization (IVF). According to the type and performance of assisted blastocyst hatching, the patients were divided into 3 groups: 1) 106 patients undergoing laser hatching with partial removal of the zona pellucida; 2) 103 patients having pronase hatching with complete removal of the zona pellucida; 3) 100 patients with no assisted blastocyst hatching. The degree of maturity and the quality of oocytes and embryos were assessed; hatching was monitored using light microscopy. Results. The pregnancy rates were noted to be statistically higher in Group 1 than in Groups 2 and 3; the multiple pregnancy rates were significantly lower in Group 1. Conclusion. Complete zona pellucida removal is a new approach to assisted hatching, in which, firstly, there is no mechanical separation of the cells forming the embryo, and, secondly, there is a rapid contact with endometrial cells during implantation. This contributes to the reduction of the risk of monozygotic pregnancies during the transfer of one morphologically normal blastocyst, by enhancing the effectiveness of ART programs.

in vitro fertilization, assisted reproductive technologies, blastocyst hatching, zona pellucida