Morphological embryo assessment: reevaluation

Abstract

To assess whether the pronuclear score and embryo nuclear scoring have an additive value to day 2 morphology criteria in the prediction of the implantation rate (IR). Retrospective clinical study. IVF Unit, Soroka University Medical Center. Analysis of all homogenous IVF fresh embryo transfers from 2008-2010. Morphological evaluation of pronuclear scoring, embryo nuclear scoring, and day 2 embryo morphology scoring on embryos obtained from IVF or intracytoplasmic sperm injection (ICSI) cycles. Implantation rate of homogeneous transfers. No statistical association was found between the pronuclear scoring system (Z) and IR. The pronuclear score Z3 had a significantly better performance than Z1, Z2, and Z4 (IR = 25.2%, 22%, 21.4%, and 11.8%, respectively). Assessment of the second day embryo morphology scoring (index [IDX]) was found to associate with IR. IDX1, IDX2, IDX3, IDX4, and IDX5 had an IR of 36.1%, 28%, 21.9%, 14.2%, and 0, respectively. The nuclear scoring including: 1 nucleus in all blastomeres, 1 nucleus in part of the blastomeres, no visualization, and multinucleation showed high association with IR = 32.7%, 22.9%, 14.8%, and 9.1%, respectively. The effect of the nuclear scoring on IR was lost in a multivariable analysis that included day 2 embryo morphology scoring. Our results suggest that there is no additive value in grading the zygote on day 1 or embryo nuclear scoring on day 2 to day 2 embryo morphology for the prediction of IR.