Can the noninvasive morphokinetic analysis by time‑lapse imaging replace embryo biopsy for preimplantation diagnosis?

INTRODUCTION
Success of in vitro fertilization (IVF) treatment has remained low despite advances in the field of reproductive medicine. It is now estimated that about 60–90% of all transferred embryos in IVF cycles do not implant. Hence, it can be stated that a large proportion of implantation failures are probably attributable to embryonic factors more than anything else.[1] Selecting the best possible embryo for transfer is a major challenge in assisted conception. The primary methods for selection of gametes and embryos for transfer are subjective and static. They are based on punctual, discontinuous observations providing limited information.[2,3] Embryos which are deemed most suitable for transfer are the ones that display precise growth observed at fixed times of development, e.g., fertilization (observation of pronuclei at 16–18 h postinsemination), syngamy (at 23 h); early cleavage (at 26 h postintracytoplasmic sperm injection and 28 h post‑IVF); day 2 cleavage (at 44 h); day‑3 cleavage (at 68 h); morula (at 92 h) and blastocyst formation (at 116 h). However, these standard checkpoints are not informative of particular cellular events and precise kinetics of embryonic development occurring between any two observations. Recently published studies suggest that the selection of embryo/s or blastocyst/s for transfer with the best potential for implantation should not be based only on number of cells and morphological assessment on the day of transfer.[4,5]