Dados do Trabalho

Title

Rate of euploidy and embryonic implantation of blastocysts biopsied on D6 and D7.

Objective

The objective of this study was to evaluate the rate of euploidy, from the Preimplantation Genetic Test for Aneuploidies (PGT-A), and the embryonic implantation of biopsied blastocysts in 6 days of culture (D6) and 7 days of culture (D7).

Methods

Retrospective study was conducted at Reproferty Clinic, evaluating patients who underwent infertility treatment using the intracytoplasmic sperm injection (ICSI) technique, followed by embryonic biopsy on D6 or D7, and Preimplantation Genetic Testing for Aneuploidies (PGT-A) from July/2021 to July/2023. The decision on the day of biopsy was based on the stage of embryonic development, with advanced-stage embryos at the stage of expansion and hatching undergoing biopsy on the 5th day of culture (D5), while those with lesser expansion or that had not yet hatched were kept under observation for biopsy on D6 or D7. In each report, the presence of biopsied embryos on D6 and D7 was verified, and their respective results classified them as “Euploid” and “Aneuploid”. The clinical history was used to determine whether or not embryo transfer was performed, and the transfers were classified as: no transfer, no transfer of D6/D7 embryos, positive Beta HCG, negative Beta HCG, and miscarriage. After data collection, the percentages were calculated and tabulated in spreadsheets.

Results

A total of 100 Preimplantation Genetic Testing for Aneuploidies (PGT-A) reports from different patients were examined, encompassing 348 analyzed embryos. Among these, 42 patients had embryos biopsied on Day 6 (D6), resulting in 75 embryos, with 25% being euploid and 75% aneuploid. Three patients had embryos biopsied on Day 7 (D7), resulting in 3 embryos, with 33% being euploid and 67% aneuploid. Regarding the transfer of euploid blastocysts on D6, 37% of the patients have not yet undergone the transfer, 32% did not transfer D6 embryos but transferred D5 embryos, 25% transferred one D6 embryo resulting in a negative Beta HCG test, 0% experienced a miscarriage, and only 5% transferred D6 embryos resulting in a positive Beta HCG test. Only one D7 blastocyst was euploid, and it was transferred, resulting in a positive Beta HCG test.

Conclusion

The results suggest a high prevalence of aneuploidy in D6 and D7 blastocysts and a low implantation rate of euploid D6 blastocysts, which is consistent with the literature. However, considering that advanced maternal age is a predisposing factor for delayed blastocyst growth, extending embryo culture to D6 and D7 may be a relevant strategy to increase the success rate of in vitro fertilization, necessitating an individualized assessment of each clinical case. It is important to acknowledge that this is an observational study with a limited sample size of euploid D7 blastocysts and that individual factors of the couple may influence euploidy and implantation outcomes.

Keywords

Euploidy; Aneuploidy; Embryo implantation; Day 6; Day 7.