Clin Exp Reprod Med.  2020 Dec;47(4):293-299. 10.5653/cerm.2019.03426.

Reanalysis of discarded blastocysts for autosomal aneuploidy after sex selection in cleavage-stage embryos

• Ebrahimian N
• Montazeri F
• Sadeghi MR
• Kalantar SM
• Gilany K
• Khalili MA

• KMID: 2509286
• DOI: http://doi.org/10.5653/cerm.2019.03426

Abstract

Objective
The goal of the present study was to investigate the rate of chromosomal aneuploidies in surplus embryos after sex determination at the cleavage stage. Then, the same chromosomal aneuploidies were evaluated in blastocysts after extended culture.
Methods
Sixty-eight surplus embryos were biopsied at the cleavage stage and incubated for an additional 3 days to allow them to reach the blastocyst stage. The embryos were reanalyzed via fluorescence in situ hybridization (FISH) to examine eight chromosomes (13, 15, 16, 18, 21, 22, X, and Y) in both cleavage-stage embryos and blastocysts.
Results
Although the total abnormality rate was lower in blastocysts (32.35%) than in cleavage-stage embryos (45.58%), the difference was not significant (p=0.113). However, when we restricted the analysis to autosomal abnormalities, we observed a significant difference in the abnormality rate between the cleavage-stage embryos (44.11%) and the blastocysts (17.64%, p=0.008). A higher rate of sex chromosomal abnormalities was also observed in cleavage-stage embryos (29.4%) than in blastocysts (14.70%, p=0.038).
Conclusion
The data indicated that embryo biopsy should be conducted at the blastocyst stage rather than the cleavage stage. The results also emphasized that examination of common chromosomal aneuploidies apart from sex selection cycles can be conducted in the blastocyst stage with the FISH method.

Keyword

Blastocyst; Cleavage; Discarded embryos; Fluorescence hybridization; Trophectoderm biopsy