P-244 Novel cleavage parameters to improve embryo selection

Abstract

Abstract Study question To study the impact of morphokinetic parameters during blastocyst development in the prediction of embryo ploidy. Summary answer Aneuploid embryos have aberrant kinetic behavior; the inclusion of the novel parameter st2 into embryo evaluation systems may improve blastocyst ploidy prediction, What is known already Selection of best embryo for transfer is key to success in in vitro fertilization (IVF) treatments and it is mainly based in morphokinetic criteria. Nevertheless, clinical pregnancy rates remain at ≈30%, a relatively low figure. Genetic screening of embryos may seem a great solution for this crossroad, as several studies demonstrate chromosomal alterations as one of the most common causes of abnormal embryos in IVF (and thus, poor clinical outcomes) but is an invasive technique and is not always recommended. Study design, size, duration Retrospective analysis of collected data. Participants/materials, setting, methods A total of 433 blastocysts from 96 treatments of patients for preimplantation genetic testing cycles were studied Main results and the role of chance The use of time-lapse culture systems allowed us to identify novel developmental features related to embryo ploidy. We present a new parameter, st2, detected at the beginning of the first cell cleavage as highly implicated in ploidy status (p < 0.001). Aneuploid embryos present slower developmental rates compared to euploid embryos for all of the key markers found in the study. Moreover, aneuploid embryos present aberrant behaviors and do not have a sequential development. Other previously studied parameters, including t3, t5, tSB, tB, cc2, cc3 and t5-t3 ,also present a strong associaiton with euploid chromosomal content if they take place in the optimal ranges stablished here. Limitations, reasons for caution This is a retrospective study that generates strong conclusions, but it could be interesting to test it in a prospective study. Wider implications of the findings Our results agree with previous studies showing slower and aberrant developmental rates for aneuploid embryos. In addition, we propose a novel parameter (st2) to include in the daily embryo evaluation for every clinician to avoid the bias described when using external algorithms or models. Trial registration number not applicable