Limitações e controvérsias na determinação do valor preditivo de critérios de morfologia oocitária e embrionária

Abstract

In order to increase the success rate of in vitro fertilization cycles, several studies have focused on the identification of the embryo with higher implantation potential. Despite recent advances in the reproductive medicine, based on the OMICs technology, routinely applicable methodologies are still needed. Thus, in most fertilization centers embryo selection for transfer is still based on morphological parameters evaluated under light microscopy. Several morphological parameters may be evaluated, ranging from the pronuclear to blastocyst stage. In general, despite the day of transfer, some criteria are suggested to present a predictive value for embryo viability when analyzed independently or combined. However, the subjectivity of morphological evaluation, as well as the wide diversity of embryo classification systems used by different fertilization centers shows contrasting results, making the implementation of a consensus regarding different morphological criteria and their predictive value a difficult task. The optimization of embryo selection represents a large potential to increase treatment success rates, allowing the transfer of a reduced number of embryos and minimizing the risks of multiple pregnancy.

Oocyte Morphology and Reproductive Outcomes - Case Report and Literature Review

“…Good oocyte quality includes ideal morphological characteristics, but also its ability to develop, be mature, be fertilized by a sperm and generate a competent embryo that results in a baby alive at home. However, even today, the latter are almost exclusively analyzed from an embryo point of view (Figueira et al, 2015;2010;Setti et al, 2011).…”

“…However, for this to happen the oocyte must mature, which can be understood as a sequence of events, that begins with follicular development, steroidogenesis and changes to the intra-follicular environment, followed by cytoplasmic development, with mRNA transcription and protein formation, ending with nuclear maturation (Sanchez et al 2017;Setti et al, 2011;Rienzi et al, 2011). To form a haploid oocyte, two-cell division must occur, meiosis I and meiosis II (Touati & Wassmann, 2016;Keefe et al, 2015;Figueira et al, 2015). The onset of meiosis I in women occurs in the fetal period, with some oocytes remaining in this stage for long periods, in the germinal vesicle´s form.…”

“…From the gametes involved in the human reproduction process, the oocyte seems to have a primary role in embryo and fetal outcomes, since it's there that nuclear, cytoplasmic and functional reorganizations occur, and provides the aggregation of sperm's genetic material and zygote formation (Keefe et al 2015;Vollenhoven & Hunt, 2018). Oocyte quality can be negatively affected by several factors, including lifestyle, such as smoking and alcohol consumption (Vollenhoven & Hunt, 2018;Prasad et al, 2016), obesity (Broughton & Moley, 2017), advanced woman's age (Vollenhoven & Hunt, 2018;Prasad et al, 2016;Keefe et al 2015;Figueira et al, 2015), endometriosis (Ceviren et al, 2014;Kasapoglu et al, 2018;Sanchez et al, 2017;Figueira et al, 2015) and controlled ovarian stimulation (COS), in assisted reproduction technology (ART) cycles (Figueira et al 2015;Bosch et al, 2016), in addition to genetic factors, such as hormone receptor polymorphisms, for example (Alviggi et al, 2018 ;Čuš et al, 2019).…”