The morphology of 2 pronuclear (2PN) embryos is related to the quality of day 3 embryos

Abstract

Objective: It has been reported that 2 PN morphology is positively related to blastocyst development and implantation; thus, zygote scoring may be useful as an efficient tool for embryo selection. The 2 PN score is generated from the grading of pronuclear (size and alignment), nucleoli (alignment and distribution) and cytoplasmic halo (with or without). However, the relationship between each individual factor and day 3 embryo quality has not been studied. The predictive value of zygote morphology for embryo selection needs further investigation.Design: A retrospective analysis of 706 zygote embryos from 97 patients who had IVF-ET treatment at UCSF In Vitro Fertilization program in 2001.Materials/Methods: Each embryo in this study was scored on both day 1 and day 3. 2 PN score was the sum of three scores: pronuclear (1 or 5), nucleoli (3, 4, 5) and cytoplasmic halo (3 or 5). Day 3 embryo score included cell number, fragmentation and compacting. Regression analysis and logistic regression analysis were used to find the predictive components in the 2 PN scoring system for cell number and compacting, respectively.Results: Regression analysis showed that the cytoplasmic halo (p = 0.005) and nucleoli scores (p = 0.004) were predictive of day 3 embryo cell number. Logistic regression analysis showed that both patient age (p = 0.014) and nucleoli scores (p = 0.015) were predictive of the compacting phenomenon. The pronuclear component was not predictive of both day 3 cell number and compacting.Conclusions: We found that the cytoplasmic halo and nucleoli scores were predictive of day 3 embryo cell cleavage. Both patient age and nucleoli score were related to compacting phenomenon. These data confirmed the predictive value of 2 PN grading.Supported by: N/A. Objective: It has been reported that 2 PN morphology is positively related to blastocyst development and implantation; thus, zygote scoring may be useful as an efficient tool for embryo selection. The 2 PN score is generated from the grading of pronuclear (size and alignment), nucleoli (alignment and distribution) and cytoplasmic halo (with or without). However, the relationship between each individual factor and day 3 embryo quality has not been studied. The predictive value of zygote morphology for embryo selection needs further investigation. Design: A retrospective analysis of 706 zygote embryos from 97 patients who had IVF-ET treatment at UCSF In Vitro Fertilization program in 2001. Materials/Methods: Each embryo in this study was scored on both day 1 and day 3. 2 PN score was the sum of three scores: pronuclear (1 or 5), nucleoli (3, 4, 5) and cytoplasmic halo (3 or 5). Day 3 embryo score included cell number, fragmentation and compacting. Regression analysis and logistic regression analysis were used to find the predictive components in the 2 PN scoring system for cell number and compacting, respectively. Results: Regression analysis showed that the cytoplasmic halo (p = 0.005) and nucleoli scores (p = 0.004) were predictive of day 3 embryo cell number. Logistic regression analysis showed that both patient age (p = 0.014) and nucleoli scores (p = 0.015) were predictive of the compacting phenomenon. The pronuclear component was not predictive of both day 3 cell number and compacting. Conclusions: We found that the cytoplasmic halo and nucleoli scores were predictive of day 3 embryo cell cleavage. Both patient age and nucleoli score were related to compacting phenomenon. These data confirmed the predictive value of 2 PN grading. Supported by: N/A.