Chromosomal Status Assessed by CGH after a Day-3 Biopsy, in Embryos Classified by Standard Scoring Methodology at Pronuclear, Cleavage and Blastocyst Stage

Abstract

Background: The standard scoring methodology, combined with blastocyst culture remains a valuable tool for embryo selection. Nevertheless, the embryo assessment based exclusively on morphological traits does not provide information about the chromosomal status of the embryo. Objective:The purpose of the present study has been to investigate the association between embryo morphology and chromosomal ploidy. Materials and methods:A total of 196 embryos resulting of 30 PGS cycles were biopsied on day 3 and tested for aneuploidies by comparative hybridization array. The embryos were classified into groups according to their morphology at zygote, cleavage and blastocyst stage.Results: Significantly statistical differences in embryo ploidy were observed when optimal day 3 morphology embryos were compared to medium morphology embryos (30.63% versus 17.28% respectively). A significantly higher proportion of euploid embryos were found in the group that achieved the blastocyst stage than in the arrested embryos group (42.57% versus 7.36%). Conclusion:The results provide evidence that embryo morphology and aneuploidy are linked both at day 3 and blastocyst stage. However the chromosomal status of the embryo may not be predicted relying exclusively on morphological assessment.