O-063 Impact of group embryo culture vs individual embryo culture strategies on blastocyst rate and quality

Abstract

Abstract Study question Does group embryo culture improve blastocyst formation compared to individual culture? Summary answer Individual culture provides an increased blastocyst formation rate. What is known already Embryo culture is one of the most important steps of an IVF treatment. Several studies pointed out that group embryo culture could help embryos with lower potential, through paracrine signaling, to achieve development and improve blastocyst formation rate. On the other hand, this issue continues to be controversial and other studies did not find differences in embryo development when using either method. Study design, size, duration A prospective randomized study was performed between January 2020 and December 2021. The data were obtained from 830 embryos that came from 103 egg donation treatments. We defined two groups: individual vs group culture. The number of embryos analyzed in the study was calculated to test a difference of 10% in the rate of blastocyst formation between the two groups. Participants/materials, setting, methods A total of 103 ICSI-egg donation cycles with normozoospermic males (fresh samples) were included. After fertilization assessment, zygotes were randomized into two groups; Group 1: individual culture (399 embryos), and Group 2: culture of 2-5 embryos per drop (431 embryos). The embryos were cultured in 35 µl drops of Global Total medium until day 5 when they were classified morphologically according to Gardner criteria (1998). The statistical analysis was performed using SPSS (version 20.0). Main results and the role of chance The rate of high-quality embryos on day 3 were similar in Group 1 compared to Group 2 (79.2% vs 81.4%, p = 0.432). However, we observed an increase in the blastocyst formation rate on day 5 (62.9% vs 56.1%, p = 0.048) and a trend for higher embryo quality (A/B blastocysts) (55.9% vs 52%, p = 0.266) in Group 1; compared to Group 2, respectively. Our data suggest that individual culture increases blastocyst formation rate and may benefit embryo quality on day 5. Our results challenge previous reports suggesting that culture in groups can improve embryo development. As hypothesis, we argue that some of the components that the embryos release to the culture environment during their division may affect the quality of the cohort potentially compromising further development up to the blastocyst stage. Limitations, reasons for caution The study is focused on laboratory outcomes until the blastocyst stage. Clinical outcomes were not analyzed. Wider implications of the findings Finding the most appropriate embryo culture conditions is essential to improve ART results. Time-lapse systems should be adapted to the use of both individual and group culture dishes. Larger randomized studies are needed in order to reach robust conclusions on the subject. Trial registration number NA