Criopreservação oocitária: desempenho reprodutivo na fertilização assistida.

AUTOR(ES)

Alvaro Petracco

DATA DE PUBLICAÇÃO

2006

RESUMO

The advance of in vitro fertilization (IVF) caused the emergence of a few dilemmas that forcibly led to deep reflections, standing out among these the questioning about the destination of excess embryos originated from this technology. In view of the controversy observed in several cultures as to ethic, moral, religious, political and scientific issues related to this embarassing situation, it became necessary to develop mechanisms that can solve or soften the controversies; thus, oocyte cryopreservation techniques were created and improved to store in a viable way unfertilized genetic material. The research sought to assess the reproductive performance of women subjected to assisted reproduction techniques by intracitoplasmátic sperm injection (ICSI) of spermatozoa from cryopreserved oocytes. A group of 16 women (GO) collected 362 oocytes, of which 204 (GOf) were fertilized by the ICSI technique after fresh follicle aspiration, and the remaining (158) were frozen; of these, the ones that survived (99) to subsequent thawing (GOc) were also fertilized. The second group (GE), formed by 32 women, had its excess embryos frozen and subsequently thawed (117). In the GO group, comparisons were carried out for rates of fertilization, cleavage and embryo quality between GOf and GOc. For the GE group, comparisons were made with embryos originated from thawed oocytes for rates of thawing survival, embryo implant and clinical pregnancy. In the analysis, women under 40 years old were included, except for those with immune or uterine factor, bad responders and participants in the oocyte donation program. The statistical tests Chi-Square, Fishers exact test, Relative Risk, and Mann-Whitney were employed. In the comparison for fertilization, cleavage and embryo quality rates between GOf and GOc oocytes, no significant differences were observed (p=0.59, p=0.56 and p=0.21, respectively). Regarding an adequate cleavage speed, embryos from GOc showed a significant delay in the speed of cell division as compared to those from GOf. There was a significant difference in the comparison of survival rates between GE embryos and GOc oocytes; while the latter had 37.3% of inviability after thawing, the former had only 22.4% (p=0.01). When embryo implantation and clinical pregnancy rates were compared between GE and GOc embryos, no significant difference was observed in the two events (p=0.06 and p=0.20, respectively). The present study shows that the reproductive performance of women subjected to in vitro fertilization with cryopreserved or fresh oocytes is similar in most analyzed aspects. Based on the results, the study suggests oocyte cryopreservation as an alternative to thawing and storage of human embryos.

ASSUNTO(S)

cryopreservation assisted reproduction techniques criopreservação injeções de esperma intracytoplasmic sperm injection técnicas reprodutivas in vitro fertilization ginecologia e obstetricia ginecologia oocytes

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