Morphokinetic parameters as auxiliary criteria for selection of blastocysts cultivated in a time-lapse monitoring system

OBJECTIVE: To describe embryonic profile up to blastocyst stage in a time-lapse system. METHODS: A retrospective, longitudinal, analytical study of patients submitted to in vitro fertilization. The embryos were grouped according to the degree of expansion, internal cell mass and trophectoderm classification, the morphokinetic parameters were associated with the time periods stated in each evolution phase. RESULTS: The appearance of a second polar corpuscle (CPap) occurred earlier in the embryos classified as excellent (2.99h; p<0.05), in relation to the embryos classified as good (3.40h), average (3.48h) and poor (3.55h). The embryos classified as excellent took less time for the pronuclei to disappear (PNbd) (21.80h; p<0.05), when compared to the good embryos (22.96h), the average (23.21h) and the poor (23.47h). As for the morphokinetic parameter, the end of the two-cell division (T2) occurred first in the excellent blastocysts (24.38h; p<0.05), when compared to the other groups: good (25.57h), average (25.53h) and poor (25.78h). With respect to synchronization with the division of three to four cells (S2), the poor embryos presented longer times for such division to occur (3.67h; p<0.05). When compared to the embryos from the groups excellent (1.97h), good (2.70h) and average (2.09h). At the time point of the blastocoel formation (TB), the excellent embryos (104.04h) did not differ from the good embryos (104.10h). However, when compared to average (107.27h) and poor (106.86h) embryos, there was statistical significance (p<0.05). CONCLUSIONS: Embryos of better quality had a shorter time in some morphokinetic parameters when compared to the other groups, thus increasing the possibilities to establish new parameters for the classification and selection of embryos.