P-176 Morphokinetic Expressions Predict Day Five Embryo Quality and Implantation - A Prospective Observational Study

Abstract Study question The aim of this prospective study was to investigate the value of human embryo morphokinetics as predictors of day 5 embryo quality and implantation. Summary answer Day 5 embryo quality was predicted best by Cleavage Synchronicity 2-8-cell stage (CS2-8). Implantation was predicted best by the time to the expanded blastocyst (tEB-tPNf). What is known already Time-lapse imaging technology enables embryologists to observe and assess not only embryo morphology but also kinetics and cleavage synchronicity. It was found that time intervals like time from 5- to 8-cell stage (s3 = t8 - t5) can predict blastocyst formation. Cetinkaya et al. defined four relative morphokinetic expressions describing cleavage synchronicity: Cleavage Synchronicity 2-8-, 4-8-, 2-4-cell stage (CS2-8, CS4-8, CS2-4) and DNA Replication time ratio (DR). In a retrospective study they found that CS2-8 followed by s3, and CS4-8 were better predictors of blastocyst quality than absolute cleavage time points (https://doi.org/10.1007/s10815-014-0341-x). Study design, size, duration This prospective observational study was conducted between December 2020 and October 2021 at a single university hospital. Patients between 18 and 45 years who underwent stimulated IVF or ICSI treatment with embryo culture in a time-lapse incubator were included. Exclusion criteria were endometriosis, PCOS, history of chemotherapy, PGT cycles and end of culture before day 5. Every patient was included only once (n = 100). Implantation was assessed for all patients with embryo transfer. Participants/materials, setting, methods Embryos (n = 298) reaching at least 8-cell stage were annotated for morphokinetics and divided into four groups based on day 5 morphology: top (TQ; n = 60), good (GQ; n = 69), poor quality (PQ; n = 105) or not reaching blastocyst stage (AE; n = 64). Absolute times were normalized to fading of pronuclei (tPNf). ROC-analysis was performed to test how morphokinetics predict quality and implantation (only known-implantation-data; n = 110). Main results and the role of chance To predict day 5 embryo quality, four morphokinetic expressions had an Area Under the Curve (AUC) of more than 0.7, including CS2-8 (AUC = 0.732), CS4-8 (AUC = 0.717), s3 (AUC = 0.724) and the start of blastulation (tSB-tPNf) (AUC = 0.725). All morphokinetic expressions mentioned were significantly different between TQ plus GQ versus PQ plus AE embryos (p < 0.001). Additionally, the data of each morphokine