Towards the selection of embryos with the greatest implantation potential

Choosing the most suitable embryo remains challenging as the standard approach to select top-quality embryos for transfer rely on static morphological assessment. It is completed after fertilisation, on days 3 and 5 post oocyte retrieval and evaluates the size and number of blastomeres, presence of nucleation and percentage of fragmentation for cleavage stage embryos. Because of the limited number of observations during the morphological assessment, morphokinetic development of embryos has been implemented. It shows a broader image of embryo behaviour with precise evaluation of the timing of events. Yet, studies are inconsistent and debatable in predicting the parameters to identify chromosomal abnormalities. Pre-implantation genetic testing detects dysmorphic embryos and correlate their developmental potential to the assessed morphology. However, the clinical utility of PGT-aneuploidy remains controversial. The future relies on newly described scoring systems such as artificial intelligence and non-invasive PGT, yet their application and actual success rate still lacks supportive evidence.