How much have we learned from time-lapse in clinical IVF?

Abstract

Can the time-lapse system (TLS) identify the best embryo for transfer? Although there are several studies that support this hypothesis, more research is required to improve the quality of the current evidence and also to assess live birth rate, miscarriage, stillbirth or clinical pregnancy in order to choose between a TLS or conventional incubation. In addition, although some authors report on effectiveness and safety in the use of TLS monitoring of embryo development in vitro, other authors that have not found relevant differences between the two systems for the culture and subsequence embryo selection. On the other hand, TLS has emerged as a novel technology and has been introduced into clinical practice in many laboratories to perform embryo morphology evaluation and study developmental kinetics in ART. However, most studies only assess blastocyst formation or implantation rate as the primary end-point and additional data are required, for example, about live birth, monozygotic twinning rates and health problems. Furthermore, the features of populations studies are varied; for example, female and male age, seminal characteristics and female factor. The embryo culture conditions and culture medium used also vary. For this review, a search of PubMed was conducted to retrieve relevant studies regarding use of TLS in embryo incubation and selection, and compare them with standard embryo culture and evaluation.

Duration of blastulation may be associated with ongoing pregnancy rate in single euploid blastocyst transfer cycles

“…This has been successful in permitting uninterrupted in-vitro culture conditions and assessing dynamic pre-implantation embryo development. With timelapse assessment, morphological events closely correlated with embryo development and IVF outcome can be closely monitored (Castello et al, 2016). Time-lapse morphokinetic (TLM) assessment may be a valuable tool for predicting blastocyst formation and to de-select embryos with a low probability of implantation (Liu et al, 2016).…”

Are cleavage anomalies, multinucleation, or specific cell cycle kinetics observed with time-lapse imaging predictive of embryo developmental capacity or ploidy?

“…Time-lapse (TL) imaging of developing embryos offers more accurate quantification of cellular kinetics and cell cycle events than was possible with conventional static morphology assessment. A wide array of kinetic markers have been proposed to be predictive for continued embryonic development and blastocyst formation (8,(10)(11)(12)(13)(14)(15)(16). TL has also revealed the prevalence of specific dysmorphisms such as multinucleation (MU), reverse cleavage (RC), direct uneven cleavage (DUC), and irregular chaotic division (ICD) in human preimplantation embryos (10,(17)(18)(19)(20).…”

Prediction of blastocyst development and implantation potential <i>in utero</i> based on the third cleavage and compaction times in mouse pre-implantation embryos

“…Several studies have focused on identifying independent and useful predictors that can be used to select high-quality embryos in IVF laboratories [3,4,5,6,7,8,9,10]. A monitoring system to observe morphology during the course of in vitro pre-implantation embryonic development has been proposed [5,6,7,8,9,10,11]. Pre-implantation embryos with normal morphology may have chromosomal abnormalities, but can nonetheless reach the blastocyst stage.…”