Dados do Trabalho

Title

An observational study involving 440 screened embryos: correlation between euploidy, morphology, maternal age and blastocyst stage (Day 5/Day 6)

Objective

The embryo cryopreservation technique combined with preimplantation genetic screening has been widely used to optimize results in treatments of In Vitro Fertilization (IVF). The objective was to determine the correlation between conventional blastocyst morphological evaluation, blastocyst stage (Day 5/Day 6) and chromosomal composition of these embryos into different age groups.

Methods

Retrospective observational study from 2020 to 2023, including 440 embryos biopsied and analyzed by Next Generation Sequence for Preimplantation Genetics Test for aneuploidies. Data were collected from blastocyst morphology, blastocyst stage (Day 5/Day 6), euploidy rate and number of chromosomal alterations, from patients submitted to IVF treatment. Data were categorized in: age (G1: <35 years; G2: 35-37 years; G3: 38-40 years; G4: >41 years), blastocyst morphology (Excellent: AA; Good: AB/BA; Average: BB/AC/CA; Poor: BC/CB/CC) and blastocyst stage (Day 5 – 120 hours post-ICSI; Day 6 – 144 hours post-ICSI). Inclusion criteria: fresh and cryopreserved oocytes, homologous and heterologous; and ejaculated and surgically retrieved, fresh and cryopreserved, homologous and heterologous semen, only embryos who reached the expanded stage on day 5 or day 6. Statistical analysis was performed using a two-porportions Z-test (p<0.05).

Results

For general euploidy rate, there was no difference (p>0.05) between Day 5 (48.2%) and Day 6 embryos (38.6%). According to the age, it was observed that in G1, the euploidy rate was similar between Day 5 and Day 6 (57.1% and 42.9% respectively, p>0.05), however, in the other groups, this rate was higher (p<0.05) on Day 5 (G2: 66.0% vs 34.0%; G3: 77.5% vs 22.5%; and G4: 80.0% vs 20.0%). In groups G1, G2 and G3 there was a higher aneuploidy rate in poor embryos (51.4%; 45.5%, 36.3% respectively, p<0.05) compared to excellent embryos (10.8%; 9.1%; 23.5%), good (18.9%; 21.8%; 18.6%) and average (18.9%, 23.6% and 21.6%) for the same age groups, while in the G4 group, there was no difference (p>0.05) for the aneuploidy rate between the blastocyst morphologies (Excellent: 14.4%; Good: 24.4%; Average: 30.6% and Poor: 30.6%). In all groups, there was a higher percentage (p<0.05) of embryos with only 1 chromosomal alteration (G1: 70.3%; G2: 76.4%; G3: 58.8%; G4: 58.0%) when compared with 2, 3 or multiple alterations. Embryos with multiple abnormalities appear evenly distributed between age groups (G1: 10.8%; G2: 5.5%; G3: 7.9% and G4: 6.0%, p>0.05).

Conclusion

In patients aged ≥35 years, faster growing blastocysts (Day 5) had higher euploidy rate. The relationship between morphology and euploidy in patients up to 40 years old, indicated that poor embryos showed a higher aneuploidy rate. However, >41 years old, all morphology should be considered for biopsy because in this group the traditional morphology selection cannot be used as euploidy predictive, justifying the strong indication of preimplantation genetic screening. These data can collaborate for the individualization of cases and optimizing the cycle management in the embryology laboratory, helping patients regarding the chances of finding euploid embryos in their age group and blastocyst quality.

Keywords

Blastocyst, Morfology, D5/D6, Euploidy.