Beyond Spherical: Unveiling the Significance of Oval Blastocyst Morphology on Euploidy and Implantation Success

The selection of the most suitable embryo, based on the morphology and shape, for embryo transfer is a critical aspect of the in vitro fertilization (IVF) process, as its precision can significantly enhance the overall effectiveness of IVF and contribute to a healthy birth. This study aimed to compare the chromosomal status and implantation potential of oval-shaped blastocysts versus normal-shaped blastocysts on day 5 post-ICSI (intracytoplasmic sperm injection). Initially, the frequency of oval blastocysts was assessed by analyzing 1328 embryos from 610 ICSI cycles. Subsequently, 80 patients undergoing ICSI and PGT-A (preimplantation genetic testing for aneuploidy), who had both normal and oval blastocysts in the same cycle, were selected to evaluate the euploid rate relative to blastocyst morphology. Finally, the implantation outcomes of fresh embryo transfers involving oval and normal-shaped blastocysts, neither of which had undergone PGT-A, were analyzed. Half of the blastocysts from each group were transferred after assisted hatching (AH), and the other half were transferred without AH. Blastocyst shape does not appear to correlate with an increased risk of aneuploidy but does influence hatching ability. Following AH, the implantation potential of elongated blastocysts is equivalent to that of normally shaped blastocysts, suggesting AH is beneficial for oval embryos. Consequently, the transfer of oval blastocysts is considered as safe and effective as the transfer of normally shaped embryos.