Dados do Trabalho

Title

Development and chromosomal constitution of blastocysts in ICSI cycles with sequential culture until the 7th day: A retrospective cohort study.

Objective

To investigate the development and chromosomal constitution of blastocysts after sequential culturing until the 7th day of embryonic development.

Methods

This retrospective cohort study included patients undergoing intracytoplasmic sperm injection (ICSI) cycles between January 2020 and April 2023 at the Valencian Institute of Infertility in Salvador. A total of 57 patients were included in the study. 487 metaphase II (MII) oocytes were inseminated, and the resulting embryos were subjected to extended culture to assess blastocyst formation on day 7. The following data were collected and analyzed: oocyte age, procedure performed (oocyte donation, ICSI with or without preimplantation genetic diagnosis), as well as the formation and euploidy rate of embryos that reached the blastocyst stage on the 7th day of development.

Results

The mean age of the oocytes used in this study was 36.2 ± 2.8 years. Regarding the type of procedure performed, 53% of cycles corresponded to intracytoplasmic sperm injection (ICSI) with preimplantation genetic diagnosis, 31% were ICSI cycles without genetic diagnosis, and 16% were oocyte donation. In total, 487 metaphase II (MII) oocytes were subjected to ICSI, resulting in a fertilization rate of 77.61% with the formation of 187 blastocysts, representing 49.47% of the total number of embryos. 42.78%(80) of blastocysts were formed on the 7th day of embryonic development. For the analysis of chromosomal constitution, 33 embryos were submitted to pre-implantation genetic diagnosis, of which 60.60%(20) were considered euploid, 33.33%(11) presented aneuploidy, and 6.07%(2) still are pending the outcome of the analysis.

Conclusion

Based on the analysis of the data collected in this study, it was evidenced that extending the culture of slow developing embryos until the 7th day (D7), and not discarding them on the 6th day (D6), is a viable approach The results revealed a significant number of high-quality blastocysts and a favorable rate of euploidy, providing cruciais insights for selecting embryos with the potential for successful implantation, thereby improving clinical outcomes and the health of live births. Based on the results obtained it is recommended extended blastocyst culture until the 7th day of embryonic development, applying this practice into the clinical and laboratory routine to improve the results of in vitro fertilization cycles. This approach represents a significant advance in the assisted reproduction field and may contribute to the success of fertility procedures in patients undergoing such cycles. However, it is important to carry out more studies to expand understanding and improve clinical practices related to embryonic development.

Keywords

: Blastocysts, Day 7 of development, Preimplantation Genetic Diagnosis, In Vitro Fertilization, Euploidy.