Establishment and clinical efficacy comparison of day 4 embryo evaluation protocol based on blastocyst quality
10.3760/cma.j.cn101441-20250515-00230
- VernacularTitle:基于囊胚质量的第4天胚胎评分方案建立及临床效能比较
- Author:
Yasong GENG
1
;
Bo ZHENG
;
Haoyang DAI
;
Linlin TAO
;
Guozhen LI
;
Zhiwei YANG
;
Shusong WANG
;
Fangfang DAI
Author Information
1. 邢台美和生殖与遗传医院生殖医学中心 邢台市生殖医学重点实验室，邢台 054000
- Publication Type:Journal Article
- Keywords:
Embryo?transfer;
Embryo?implantation;
Morula;
Compaction;
Day 4 embryo scoring
- From:
Chinese Journal of Reproduction and Contraception
2025;45(11):1131-1138
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To establish a day 4 embryo evaluation protocol by analyzing embryonic characteristics affecting blastocyst formation, and validate its clinical effectiveness.Methods:This retrospective cohort study included clinical data from 1 037 patients who underwent fresh in vitro fertilization and embryo transfer (IVF-ET) on day 4 in Center for Reproductive Medicine of Xingtai Meihe Reproductive and Genetic Hospital between January 2018 and April 2024. Morphological assessments were performed at (92±2) h post-fertilization. After excluding 1 326 embryos selected for fresh transfer, 2 723 embryos underwent blastocyst culture. To address selection bias in transferred embryos, the scoring system was primarily based on high-quality blastocyst formation rates. Multivariate binary regression analysis evaluated how day 4 developmental stage, fragmentation rate, stage-specific cleavage patterns, multinucleation/vacuolization affected transferable blastocyst formation rate and high-quality blastocyst rate. Regression coefficients determined parameter weights for high-quality blastocyst formation, establishing a day 4 embryo scoring protocol that compared outcomes across different grades. The scoring system was validated by comparing transferable blastocyst formation rate, high-quality blastocyst rate, and implantation rate among different day 4 embryo grades. All embryos were further rescored according to three previously reported evaluation schemes [Feil 2008, Gemma 2015, and European Society of Human Reproduction and Embryology (ESHRE) 2011]. The predictive values of these three day 4 scoring systems and the day 4 scoring system established in this study were compared using the area under the curve (AUC) receiver operating characteristic (ROC) curve in predicting the formation rate of transferable blastocyst, the formation rate of high-quality blastocyst, and implantation rate. Results:In the prediction of high-quality blastocyst formation, early blastocyst showed the highest influence weight compared to embryos with the ratio of blastomere numbers on day 4 to those on day 3 (BNR) <1.2 ( B=3.398, OR=29.915, P<0.001), followed by fragmentation <10% versus ≥50% ( B=1.263, OR=3.535, P<0.001), a stage-specific cleavage pattern ( B=0.903, OR=2.467, P=0.005), and absence of multinucleation or vacuoles ( B=0.797, OR=2.218, P=0.007). Using the newly developed day 4 scoring system, embryos were graded A, B, C, D, E. Transferable blastocyst formation rates were 88.57% (279/315), 76.99% (241/313), 56.11% (280/499), 40.27% (238/591) and 14.22% (143/1 005), respectively; high-quality blastocyst rates were 51.42% (162/315), 35.46% (111/313), 20.04% (100/499), 9.47% (56/591) and 3.98% (40/1 005). All inter-group differences were statistically significant (all P<0.005). Implantation rates for transferred embryos of grades A-E declined sequentially: 63.18% (381/603), 56.19% (322/573), 38.29% (54/141), 26.53% (13/49) and 9.67% (3/31). The day 4 embryo scoring system proposed in this study demonstrated significantly higher predictive efficacy for transferable blastocyst formation rate (AUC=0.812), high-quality blastocyst formation rate (AUC=0.804), and implantation rate (AUC=0.603) compared with Feil 2008 (AUC=0.797, P<0.001; AUC=0.781, P<0.001; AUC=0.585, P<0.001), Gemma 2015 (AUC=0.773, P<0.001; AUC=0.771, P<0.001; AUC=0.542, P=0.006), and ESHRE 2011 (AUC=0.710, P<0.001; AUC=0.745, P<0.001; AUC=0.592, P<0.001). We also observed the presence of pseudo-compacted embryo, whose transferable blastocyst formation rate [38.28% (49/128)] and high-quality blastocyst formation rate [7.03% (9/128)] were similar to those of cleavage-stage embryos with a BNR≥1.2. Conclusion:The established day 4 morphological assessment system reliably predicts the potential to transferable blastocyst and high-quality blastocyst, and effectively forecasts implantation rates.
