The effect of two embryo culture systems on blastocyst development, euploidy and mosaicism rates

Objective Culturing embryos in groups may be beneficial due to the sharing of autocrine and paracrine factors. Embryo Corral® (EC) dishes were developed to mimic group culture while allowing isolated embryo development. The objective of this study was to compare embryo development and Preimplantation Genetic Testing - Aneuploidy (PGT-A) results for embryos grown in EC dishes versus group culture. Design Retrospective study in a private IVF laboratory. Materials and methods This study examined 2,309 embryos cultured in EC dishes and 944 embryos in group culture. Embryos were divided into PGT-A and non PGT-A groups, and by autologous oocyte (AO) embryos versus donor oocyte (DO) embryos. The culture system in 2019 utilized EC dishes for PGT-A intended embryos from Day 3 after assisted hatching to time of biopsy to simulate group culture, while keeping the embryos separated. Embryos not intended for PGT-A were not hatched on Day 3 and group cultured in standard culture drops. Starting in 2020, all embryos were cultured only in standard group culture drops, regardless if they were intended for PGT-A. Embryos were cultured for 120-168 hours and a blastocyst utilization rate (BUR) was calculated for each group. In the PGT-A groups, euploidy rates were also examined. Results There were no significant differences found in BUR between non-PGT-A AO embryos group cultured in 2019 (55.0%) vs 2020 (62.3%), or in BUR in the non-PGT-A DO embryos group cultured in 2019 (65.5%) vs 2020 (73.7%). There were significant differences in BUR between PGT-A intended embryos cultured in EC dishes in 2019 and PGT-A intended embryos group cultured in 2020 in both AO embryo and DO embryo groups. For AO embryos, BUR was 42.9% in EC and 56.5% for group culture (p=0.0011). For DO embryos, BUR was 50.8% in EC and 82.9% in group culture (p Conclusions The lack of significance in BUR in the non-PGT-A groups from 2019 to 2020 shows that the culture media and conditions were stable through 2019 and 2020. Therefore, group culture resulted in higher BUR than when using the EC dishes for culturing embryos to the blastocyst stage for PGT-A testing in both DO and AO embryos. The culture systems did not impact the rate of euploidy, mosaicism, or aneuploidy. Disclosures Nothing to disclose Funding None