Description of euploid embryo implantation outcome by morphokinetic investigation

 A. Tejera, M. Stoppa, M. Meseguer, A. Capalbo, M. Florensa, F. Ubaldi, Y. Galiana, L. Rienzi

Objective

To define euploid implanted morphokinetic parameters and propose an algorithm for embryo selection based on this analysis.

Design

Retrospective observational study.

Materials and Methods

Embryo development from 265 patients undergoing pre-implantation genetic screening, euploid transferred embryos (n=342) were analyzed with time-lapse imaging (Embryoscope, Vitrolife, Denmark). Chromosomal analysis was performed through array-comparative genome hybridization and qPCR. Timing of each cellular event was annotated along embryo development (tn) in hours post ICSI, also we calculated cell cycle duration (ccn=tn+1-tn) and synchrony between blastomeres (sn=tn+1-tn). In addition, timing of compaction (tM), blastocyst formation (tB) and expansion (tEB) were recorded. The data to define morphokinetic behaviour was obtained from a total of transferred embryos, and embryos with known implantation data (KID). Only KID embryos with either full implantation (number of sacs matches the number of transferred embryos n=130) or no implantation (no biochemical pregnancy achieved n=169) were included in this analysis.

Results

A logistic regression analysis identified tM (<94.3h), followed by s2 (<1.25h) as the most relevant variables related to implantation. Based on these results a hierarchical model classifying embryos according to implantation potential was generated (grade A to D). Implantation was confirmed by the existence of a fetal heart beat at ultrasound after 7 weeks of gestation. Significant differences in implantation rates were observed between categories. More specifically grade “A” 58 %, “B” 43.9%, “C” 31.8% and “D” 25% p<0.05.

Conclusions

To our knowledge, we have described the largest dataset of euploid embryos by time-lapse analysis. We present a tentative model to be applied for embryo selection on euploid embryos in those combined cases of time-lapse with PGS. This analysis reveal significant morphokinetic differences between implanted and not implanted euploid embryos and provides a preliminary model that needs to be validated prospectively. Validation will depict its ability to predict embryo implantation and improve embryo selection by morphology on PGS program