Correlations Between Morphology Grading and Aneuploidy in Patients Undergoing Preimplantation Genetic Diagnosis

Abstract

In the IVF laboratory, embryos are typically selected for transfer based on morphology criteria from development at the pronuclear, day two and day three stages. Although pregnancy data suggests that these embryos are more likely to be chromosomally normal, it is impossible to determine chromosomal status with morphology. However, trends can be ascertained between morphology and aneuploidy in patients undergoing preimplantation genetic diagnosis (PGD). The goal of this study was to determine if any correlations exist between embryo morphology and aneuploidy status after PGD. Retrospective data analysis Embryo morphology on days one through three of culture was analyzed and compared to aneuploidy status. Embryos from patients undergoing PGD between 2004 through March of 2005 were assessed based on pronuclear morphology; cell number, evenness of cell size and multinucleation on day two and day three cell number. 1310 embryos were biopsied, Of these 1264 had accurate Z scoring, 1040 day 2 cell number, 997 day 2 symmetry; 942, nucleation score and 1310 accurate day 3 score. Percent euploid is calculated from the number scored in each category to estimate the rate of euploidy/ stage-score. Embryos with good morphology on days 2 through 3 were more likely to be euploid after PGD analysis. Tabled 1 Tabled 1*P<0.05 Tabled 1*P<0.05 *P<0.05 *P<0.05 This data suggests that embryos with good morphology with regards to Zscore, day two cell number, cell symmetry and lack of mulitnucleation and day three cell number are more likely to be chromosomally normal and therefore represent a higher implantation and pregnancy potential. The most significant correlations between morphology and aneuploidy appear to be reflected in the day two symmetry and multinucleation categories. Embryos with combined good Z-scores, day 2 morphology and day 3 morphology may be significantly less aneuploid than any others and this can be used in general IVF for transitioning to single embryo transfer.