Semiautomated analysis of embryoscope images: Using localized variance of image intensity to detect embryo developmental stages

Non invasive assessment of human oocytes and embryos in assisted reproduction: Review on present practices and future trends

Oocyte and embryo grading is one of the most important steps in assisted reproductive technology to identify the best among cultured embryos for transfer or vitrification. The most commonly used non-invasive method is morphological assessment of gametes and embryos using a microscope. This method despite being simple and cost-effective has interobserver and intraobserver variability and subjectivity and has little to offer about the physiological state of embryos. This review sourced research articles and reviews pertaining to other non-invasive assessment methodologies from Medline and PubMed to collate latest technologies in vogue and identify novel methodologies of the future. The review assesses the current understanding in oocyte and embryo grading and touches upon novel non-invasive techniques and potential biomarkers to identify the best embryo. The latest available literature on time-lapse imaging, hierarchical algorithms, omics (consisting of proteomics and secretomes), miRNAs, mitochondrial RNAs and artificial intelligence has been accessed to summarize the enormous information available, to identify gaps in current interpretations, to identify emerging technologies and to provide direction for future research. This review will greatly benefit anyone practicing assisted reproduction and clinical embryology.

Can novel early non-invasive biomarkers of embryo quality be identified with time-lapse imaging to predict live birth?

STUDY QUESTION

Can time-lapse imaging systems make it possible to identify novel early non-invasive biomarkers to predict live birth?

SUMMARY ANSWER

From mostly high-grade embryos, out of 35 morphometric, morphologic and morphokinetic variables, only pronuclei (PN) position at time of PN juxtaposition and the absence of multinucleated blastomeres at the 2-cell stage (MNB2cell), were potentially associated with live birth.

WHAT IS KNOWN ALREADY

Previous studies indicate that some kinetic markers may be predictive of blastocyst development and embryonic implantation. Certain teams have suggested including some of them in decisional algorithms for embryo transfers.

STUDY DESIGN, SIZE, DURATION

Using a time-lapse incubator (EmbryoScope, Unisense FertiliTech), we retrospectively explored the associations between the morphometric, morphologic and morphokinetic parameters of oocytes, zygotes and embryos, and their associations with live birth. This study assessed 232 embryos from single embryo transfers after ICSI cycles performed between January 2014 and December 2017.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The morphometric, morphologic and morphokinetic parameters (18, 4 and 13, respectively) of oocytes, zygotes and early embryos were studied retrospectively. The associations between these parameters were examined using a Spearman's correlation, Mann-Whitney or chi-squared test as appropriate. We examined whether these parameters were associated with outcomes in univariate and multivariate logistic regression analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

Central PN juxtaposition was associated with a 2-fold increase in the odds of live birth (OR = 2.20; 95% CI, [1.26-3.89]; P = 0.006), while the presence of MNB2cell was associated with half the odds of live birth (OR = 0.51; 95% CI, [0.27-0.95]; P = 0.035). These two parameters were independent of embryo kinetics. The 33 remaining parameters had no significant association with the capacity of transferred embryos to develop to term.

LIMITATIONS, REASONS FOR CAUTION

Even though the population size was relatively small, our analyses were based on homogeneous cycles, i.e. young women whose transferred embryos were found to be high-grade according to conventional morphology evaluation. In addition, our conclusions were established from a specific, highly selected population, so other study populations, such as women in an older age bracket, may yield different results. Finally, because we assessed day 2/3 transfers, our findings cannot be generalized to embryos cultured up to the blastocyst stage.

WIDER IMPLICATIONS OF THE FINDINGS

It would be interesting to explore, prospectively, whether PN localisation is a relevant measure to predict embryo development when added into further algorithms and whether this parameter could be suitable for use in other IVF clinics. Further studies are needed, notably to explore the added value of timing evaluation in cohorts of embryos with low or intermediate morphology grade, as well as in other maternal populations (i.e. older women).

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was used for this study. P. Sagot received funding from the following commercial companies: Merck Serono, Finox Biotech, Ferring, MSD France SAS, Teva Sante ́ SAS, Allergan France, Gedeon Richter France, Effik S.A., Karl Storz Endoscopie France, GE Medical Systems SCS, Laboratoires Genevrier, H.A.C. Pharma and Ipsen.All the authors confirm that none of this funding was used to support the research in this study. There are no patents, products in development or marketed products to declare. This does not alter the authors' adherence to all the journal policies on sharing data and materials.

Development of automated annotation software for human embryo morphokinetics

STUDY QUESTION

Is it possible to develop an automated annotation tool for human embryo development in time-lapse devices based on image analysis?

SUMMARY ANSWER

We developed and validated an automated software for the annotation of human embryo morphokinetic parameters, having a good concordance with expert manual annotation on 701 time-lapse videos.

WHAT IS KNOWN ALREADY

Morphokinetic parameters obtained with time-lapse devices are increasingly used for the assessment of human embryo quality. However, their annotation is time-consuming and can be slightly operator-dependent, highlighting the need to develop fully automated approaches.

STUDY DESIGN, SIZE, DURATION

This monocentric study was conducted on 701 videos originating from 584 couples undergoing IVF with embryo culture in a time-lapse device. The only selection criterion was that the duration of the video must be over 60 h.

PARTICIPANTS/MATERIALS, SETTING, METHODS

An automated morphokinetic annotation tool was developed based on gray level coefficient of variation and detection of the thickness of the zona pellucida. The detection of cellular events obtained with the automated tool was compared with those obtained manually by trained experts in clinical settings.

MAIN RESULTS AND THE ROLE OF CHANCE

Although some differences were found when embryos were considered individually, we found an overall concordance between automated and manual annotation of human embryo morphokinetics from fertilization to expanded blastocyst stage (r2 = 0.92).

LIMITATIONS, REASONS FOR CAUTION

These results should undergo multicentric external evaluation in order to test the overall performance of the annotation tool. Getting access to the export of 3D videos would enhance the quality of the correlation with the same algorithm and its extension to the 3D regions of interest. A technical limitation of our work lies within the duration of the video. The more embryo stages the video contains, the more information the script has to identify them correctly.

WIDER IMPLICATIONS OF THE FINDINGS

Our system paves the way for high-throughput analysis of multicentric morphokinetic databases, providing new insights into the clinical value of morphokinetics as a predictor of embryo quality and implantation.

STUDY FUNDING/COMPETING INTEREST(S)

This study was partly funded by Finox-Gedeon Richter Forward Grant 2016 and NeXT (ANR-16-IDEX-0007). We have no conflict of interests to declare.

TRIAL REGISTRATION NUMBER

N/A

Inter-laboratory agreement on embryo classification and clinical decision: Conventional morphological assessment vs. time lapse

The aim of this study is to determine inter-laboratory variability on embryo assessment using time-lapse platform and conventional morphological assessment. This study compares the data obtained from a pilot study of external quality control (EQC) of time lapse, performed in 2014, with the classical EQC of the Spanish Society for the Study of Reproductive Biology (ASEBIR) performed in 2013 and 2014. In total, 24 laboratories (8 using EmbryoScope™, 15 using Primo Vision™ and one with both platforms) took part in the pilot study. The clinics that used EmbryoScope™ analysed 31 embryos and those using Primo Vision™ analysed 35. The classical EQC was implemented by 39 clinics, based on an analysis of 25 embryos per year. Both groups were required to evaluate various qualitative morphological variables (cell fragmentation, the presence of vacuoles, blastomere asymmetry and multinucleation), to classify the embryos in accordance with ASEBIR criteria and to stipulate the clinical decision taken. In the EQC time-lapse pilot study, the groups were asked to determine, as well as the above characteristics, the embryo development times, the number, opposition and size of pronuclei, the direct division of 1 into 3 cells and/or of 3 into 5 cells and false divisions. The degree of agreement was determined by calculating the intra-class correlation coefficients and the coefficient of variation for the quantitative variables and the Gwet index for the qualitative variables. For both EmbryoScope™ and Primo Vision™, two periods of greater inter-laboratory variability were observed in the times of embryo development events. One peak of variability was recorded among the laboratories addressing the first embryo events (extrusion of the second polar body and the appearance of pronuclei); the second peak took place between the times corresponding to the 8-cell and morula stages. In most of the qualitative variables analysed regarding embryo development, there was almost-perfect inter-laboratory agreement among conventional morphological assessment (CMA), EmbryoScope™ and Primo Vision™, except for false divisions, vacuoles and asymmetry (users of all methods) and multinucleation (users of Primo Vision™), where the degree of agreement was lower. The inter-laboratory agreement on embryo classification according to the ASEBIR criteria was moderate-substantial (Gwet 0.41-0.80) for the laboratories using CMA and EmbryoScope™, and fair-moderate (Gwet 0.21-0.60) for those using Primo Vision™. The inter-laboratory agreement for clinical decision was moderate (Gwet 0.41-0.60) on day 5 for CMA users and almost perfect (Gwet 0.81-1) for time-lapse users. In conclusion, time-lapse technology does not improve inter-laboratory agreement on embryo classification or the analysis of each morphological variable. Moreover, depending on the time-lapse platform used, inter-laboratory agreement may be lower than that obtained by CMA. However, inter-laboratory agreement on clinical decisions is improved with the use of time lapse, regardless of the platform used.

Predicting pregnancy rate following multiple embryo transfers using algorithms developed through static image analysis

Single-embryo image assessment involves a high degree of inaccuracy because of the imprecise labelling of the transferred embryo images. In this study, we considered the entire transfer cycle to predict the implantation potential of embryos, and propose a novel algorithm based on a combination of local binary pattern texture feature and Adaboost classifiers to predict pregnancy rate. The first step of the proposed method was to extract the features of the embryo images using the local binary pattern operator. After this, multiple embryo images in a transfer cycle were considered as one entity, and the pregnancy rate was predicted using three classifiers: the Real Adaboost, Gentle Adaboost, and Modest Adaboost. Finally, the pregnancy rate was determined via the majority vote rule based on classification results of the three Adaboost classifiers. The proposed algorithm was verified to have a good predictive performance and may assist the embryologist and clinician to select embryos to transfer and in turn improve pregnancy rate.

Chromosomal instability in mammalian pre-implantation embryos: potential causes, detection methods, and clinical consequences

Formation of a totipotent blastocyst capable of implantation is one of the first major milestones in early mammalian embryogenesis, but less than half of in vitro fertilized embryos from most mammals will progress to this stage of development. Whole chromosomal abnormalities, or aneuploidy, are key determinants of whether human embryos will arrest or reach the blastocyst stage. Depending on the type of chromosomal abnormality, however, certain embryos still form blastocysts and may be morphologically indistinguishable from chromosomally normal embryos. Despite the implementation of pre-implantation genetic screening and other advanced in vitro fertilization (IVF) techniques, the identification of aneuploid embryos remains complicated by high rates of mosaicism, atypical cell division, cellular fragmentation, sub-chromosomal instability, and micro-/multi-nucleation. Moreover, several of these processes occur in vivo following natural human conception, suggesting that they are not simply a consequence of culture conditions. Recent technological achievements in genetic, epigenetic, chromosomal, and non-invasive imaging have provided additional embryo assessment approaches, particularly at the single-cell level, and clinical trials investigating their efficacy are continuing to emerge. In this review, we summarize the potential mechanisms by which aneuploidy may arise, the various detection methods, and the technical advances (such as time-lapse imaging, "-omic" profiling, and next-generation sequencing) that have assisted in obtaining this data. We also discuss the possibility of aneuploidy resolution in embryos via various corrective mechanisms, including multi-polar divisions, fragment resorption, endoreduplication, and blastomere exclusion, and conclude by examining the potential implications of these findings for IVF success and human fecundity.