Oocyte and embryo – how to evaluate and treat it to get the best results

The central concept of the lecture is morphokinetics — the timing of key developmental events: the appearance of pronuclei, division into two, four and more blastomeres, and the onset of compaction and cavitation. Deviations in these intervals and signs of abnormal cleavage, such as direct division from one cell into three, are associated with reduced embryo potential and serve as criteria for deselection.

Meseguer addresses the role of artificial intelligence in interpreting these data. Machine-learning algorithms process thousands of images and morphokinetic parameters, reduce inter-operator variability and produce a ranking of embryos by probability of success. Such an approach complements but does not replace the embryologist's expertise, leaving the final decision to the specialist.

A separate section is devoted to evaluating the oocyte as the starting point of the whole process. Oocyte quality largely determines the potential of the future embryo, so the morphology of the zona pellucida, the polar body and the cytoplasm, the state of the cumulus and the signs of maturity are analysed. The speaker shows how early oocyte characteristics relate to subsequent developmental dynamics and allow an earlier prognosis of the outcome.

On the basis of these data, practical treatment algorithms are built: prioritising embryos for transfer, justifying elective single-embryo transfer, deciding whether to extend culture to the blastocyst stage, and integrating morphokinetics with the results of preimplantation testing. It is stressed that any model requires validation on each individual laboratory's own data.

The practical takeaway of the lecture for the clinic is that combining continuous time-lapse observation, standardised morphokinetic criteria and artificial-intelligence algorithms increases the objectivity and reproducibility of embryo selection. This leads to more grounded transfer decisions, a potential reduction in time to pregnancy and a lower rate of multiple pregnancies.