Correlation between embryo morphology and development and chromosomal complement

Abstract

To analyze the correlation between embryo morphology and the chromosomal status using the comparative genomic hybridization (CGH) technique for screening 46 chromosomes in a single blastomere biopsy from Day 3 embryos. Retrospective study in an in vitro fertilization laboratory. Four hundred fifty two embryos were included from 63 cycle ICSI patients undergoing preimplantation genetic screening. The 46 chromosomes were analyzed by blastomere biopsy from day 3 embryos using CGH array method. Data was analyzed by Chi-Square analysis for embryo development rate, fragmentation rate and chromosome status of the analyzed blastomeres. From 452 embryos biopsied, 26 samples were not able to analyze. A total of 263/426 (61.7%) embryos tested on day 3 were abnormal. 175 blastocysts developed from biopsied embryos. 51/175 (29.1%) were analyzed as abnormal vs 124/175 (70.9%) from normal a-CGH results. The incidence of chromosomal abnormalities was significantly lower in a day 3 embryo with more than 6 cells compared with embryos with 6 cells or less (59.3% versus 74.3%, respectively). The numerical analysis of chromosomes was related to the percentage of fragmentation. In the total of 426 embryos tested, the total incidence of chromosomal abnormalities was 23.6% with 0 to 15% fragmentation and 66.1% with 15% or more fragmentation. Embryo development rate and morphological parameter such as degree of fragmentation to a large extent reflect the cytogenetic status of the embryo and thus are important in the selection of embryos with the highest implantation potential.