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Time-lapse imaging: clearly useful to both laboratory personnel and patient outcomes versus just because we can doesn't mean we should

2018; Elsevier BV; Volume: 109; Issue: 4 Linguagem: Inglês

10.1016/j.fertnstert.2018.01.042

1556-5653

Richard J. Paulson, David E. Reichman, Nikica Zaninovic, Linnea R. Goodman, Catherine Racowsky,

Renal and related cancers

Nikica Zaninovic, M.S., Ph.D., H.C.L.D., E.L.D.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Over the last 50 years, embryo culture techniques for in vitro fertilization (IVF) have continued to evolve. The latest evolution raises a controversial question—whether culturing embryos in systems which allow for undisturbed time-lapse monitoring (TLM) improve our fundamental understanding of embryogenesis, and whether that understanding can reliably translate into improved clinical outcomes (1Zaninovic N. Irani M. Meseguer M. Assessment of embryo morphology and developmental dynamics by time-lapse microscopy: is there a relation to implantation and ploidy?.Fertil Steril. 2017; 108: 722-729Abstract Full Text Full Text PDF PubMed Scopus (51) Google Scholar). Our charge in this Fertile Battle was to provide affirmation to a series of questions regarding the fundamental utility of this technology. Prior to addressing these questions, a brief declaration of sorts is required. For better or worse, the field of reproductive medicine has been increasingly compressed into a one-size-fits-all approach, in which vigorous stimulation, blastocyst culture, freeze-all cycles, and preimplantation genetic screening (PGS) is the universal recipe, regardless of expense, patient age, prognosis, prior history, or embryo development. We concede that for clinics with exclusive adoption of PGS, nuanced evaluation of embryo morphokinetics, and cleavage patterns may add only marginal refinement to embryo selection. For others, however, there is much potential benefit. This is not to say that we don't favor fewer embryos transferred, that the majority of our transfers are not blastocyst stage, or that we don't perform PGS when indicated. But it is to say that we don't practice medicine in a one-size-fits-all approach, and the chief benefit of TLM may well be found in clinics where ongoing embryo evaluation is an essential and integrated aspect of patient care. It is well known that disturbances in gas composition, pH, and temperature can adversely affect embryo development. Indeed, the move away from "big box" incubators towards smaller tabletop incubation and isolated culture of individual embryos underscores the benefits of tight homeostasis. Conventional static embryo assessment involves the disturbance of embryos on a near-daily basis, whereas "single shot" evaluation offers incomplete assessment that can miss key developmental events. TLM, on the other hand, involves only a single culture media change, or no disturbance when employing single stage media (2Costa-Borges N. Belles M. Meseguer M. Galliano D. Ballesteros A. Calderon G. Blastocyst development in single medium with or without renewal on day 3: a prospective cohort study on sibling donor oocytes in a time-lapse incubator.Fertil Steril. 2016; 105: 707-713Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar). Limiting the frequency of embryo evaluations has been associated with a significant increase in high scoring blastocysts and number of embryos frozen (3Zhang J.Q. Li X.L. Peng Y. Guo X. Heng B.C. Tong G.Q. Reduction in exposure of human embryos outside the incubator enhances embryo quality and blastulation rate.Reprod Biomed Online. 2010; 20: 510-515Abstract Full Text Full Text PDF PubMed Scopus (70) Google Scholar). In addition to offering improved culture conditions in small volume media at low oxygen concentration, TLM enables us to evaluate dynamic developmental events and the speed at which they occur, factors that are associated with ploidy and impact reproductive competence (4Del Carmen Nogales M. Bronet F. Basile N. Martinez E.M. Linan A. Rodrigo L. et al.Type of chromosome abnormality affects embryo morphology dynamics.Fertil Steril. 2017; 107: 229-235.e2Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar, 5Dal Canto M. Coticchio G. Mignini Renzini M. De Ponti E. Novara P.V. Brambillasca F. et al.Cleavage kinetics analysis of human embryos predicts development to blastocyst and implantation.Reprod Biomed Online. 2012; 25: 474-480Abstract Full Text Full Text PDF PubMed Scopus (173) Google Scholar, 6Wale P.L. Gardner D.K. The effects of chemical and physical factors on mammalian embryo culture and their importance for the practice of assisted human reproduction.Hum Reprod Update. 2016; 22: 2-22Crossref PubMed Scopus (166) Google Scholar). Such systems do not exhibit adverse effects on embryos, and have been associated with reassuring perinatal outcomes (7Insua M.F. Cobo A.C. Larreategui Z. Ferrando M. Serra V. Meseguer M. Obstetric and perinatal outcomes of pregnancies conceived with embryos cultured in a time-lapse monitoring system.Fertil Steril. 2017; 108: 498-504Abstract Full Text Full Text PDF PubMed Scopus (20) Google Scholar). With so much to learn in this critical early window, why would we not want to observe as much as possible? TLM has greatly increased our ability to detect early developmental milestones such as fertilization, cytokinesis and karyokinesis, as well as to determine normal and abnormal cleavage dynamics. In recent papers, Coticchio et al. (8Coticchio G. Mignini Renzini M. Novara P.V. Lain M. De Ponti E. Turchi D. et al.Focused time-lapse analysis reveals novel aspects of human fertilization and suggests new parameters of embryo viability.Hum Reprod. 2018; 33: 23-31Crossref PubMed Scopus (67) Google Scholar) describe fertilization events not previously recognized, and Derrick et al. (9Derrick R. Hickman C. Oliana O. Wilkinson T. Gwinnett D. Whyte L.B. et al.Perivitelline threads associated with fragments in human cleavage stage embryos observed through time-lapse microscopy.Reprod Biomed Online. 2017; 35: 640-645Abstract Full Text Full Text PDF PubMed Scopus (10) Google Scholar) describe for the first time perivitelline threads and their association with fragmentation. Analysis of TLM findings have also led to an understanding that kinetic markers predict embryo developmental competence. Meseguer et al. (10Meseguer M. Herrero J. Tejera A. Hilligsoe K.M. Ramsing N.B. Remohi J. The use of morphokinetics as a predictor of embryo implantation.Hum Reprod. 2011; 26: 2658-2671Crossref PubMed Scopus (614) Google Scholar) defined kinetic parameters associated with implantation. Embryos that cleave earlier and maintain a synchronized speed of development have the highest potential to reach blastocyst, receive better morphologic scores than their slower developing counterparts, and implant at a higher rate (5Dal Canto M. Coticchio G. Mignini Renzini M. De Ponti E. Novara P.V. Brambillasca F. et al.Cleavage kinetics analysis of human embryos predicts development to blastocyst and implantation.Reprod Biomed Online. 2012; 25: 474-480Abstract Full Text Full Text PDF PubMed Scopus (173) Google Scholar, 11Cruz M. Garrido N. Herrero J. Perez-Cano I. Munoz M. Meseguer M. Timing of cell division in human cleavage-stage embryos is linked with blastocyst formation and quality.Reprod Biomed Online. 2012; 25: 371-381Abstract Full Text Full Text PDF PubMed Scopus (204) Google Scholar, 12Hashimoto S. Kato N. Saeki K. Morimoto Y. Selection of high-potential embryos by culture in poly (dimethylsiloxane) microwells and time-lapse imaging.Fertil Steril. 2012; 97: 332-337Abstract Full Text Full Text PDF PubMed Scopus (101) Google Scholar, 13Desai N. Ploskonka S. Goodman L.R. Austin C. Goldberg J. Falcone T. Analysis of embryo morphokinetics, multinucleation and cleavage anomalies using continuous time-lapse monitoring in blastocyst transfer cycles.Reprod Biol Endocrinol. 2014; 12: 54Crossref PubMed Scopus (109) Google Scholar, 14Kirkegaard K. Kesmodel U.S. Hindkjaer J.J. Ingerslev H.J. Time-lapse parameters as predictors of blastocyst development and pregnancy outcome in embryos from good prognosis patients: a prospective cohort study.Hum Reprod. 2013; 28: 2643-2651Crossref PubMed Scopus (171) Google Scholar, 15Milewski R. Kuc P. Kuczynska A. Stankiewicz B. Lukaszuk K. Kuczynski W. A predictive model for blastocyst formation based on morphokinetic parameters in time-lapse monitoring of embryo development.J Assist Reprod Genet. 2015; 32: 571-579Crossref PubMed Scopus (77) Google Scholar, 16Milewski R. Milewska A.J. Kuczynska A. Stankiewicz B. Kuczynski W. Do morphokinetic data sets inform pregnancy potential?.J Assist Reprod Genet. 2016; 33: 357-365Crossref PubMed Scopus (30) Google Scholar). Analysis of such data allows for more rigorous allocation of patients between cleavage stage and blastocyst transfer. In addition to these findings, TLM has allowed for the discovery of aberrant morphological events that would otherwise remain unidentified. Direct unequal cleavage (DUC) in which one blastomere divides into three is perhaps the event most correlated with reduced blastulation and lower implantation (17Rubio I. Kuhlmann R. Agerholm I. Kirk J. Herrero J. Escriba M.J. et al.Limited implantation success of direct-cleaved human zygotes: a time-lapse study.Fertil Steril. 2012; 98: 1458-1463Abstract Full Text Full Text PDF PubMed Scopus (221) Google Scholar, 18Zhan Q. Ye Z. Clarke R. Rosenwaks Z. Zaninovic N. Direct Unequal Cleavages: embryo developmental competence, genetic constitution and clinical outcome.PLoS One. 2016; 11: e0166398Crossref PubMed Scopus (68) Google Scholar, 19Athayde Wirka K. Chen A.A. Conaghan J. Ivani K. Gvakharia M. Behr B. et al.Atypical embryo phenotypes identified by time-lapse microscopy: high prevalence and association with embryo development.Fertil Steril. 2014; 101 (e1–5): 1637-1648Abstract Full Text Full Text PDF PubMed Scopus (118) Google Scholar). Multinucleation, the detection of which is superior with TLM, has been associated with a three-fold increase in DUCs (20Aguilar J. Rubio I. Munoz E. Pellicer A. Meseguer M. Study of nucleation status in the second cell cycle of human embryo and its impact on implantation rate.Fertil Steril. 2016; 106: 291-299.e2Abstract Full Text Full Text PDF PubMed Scopus (24) Google Scholar, 21Ergin E.G. Caliskan E. Yalcinkaya E. Oztel Z. Cokelez K. Ozay A. et al.Frequency of embryo multinucleation detected by time-lapse system and its impact on pregnancy outcome.Fertil Steril. 2014; 102: 1029-1033.e1Abstract Full Text Full Text PDF PubMed Scopus (46) Google Scholar). Another phenomenon involving blastomere fusion is dubbed reverse cleavage which can occur at any stage during embryo culture and significantly compromises reproductive outcomes (22Liu Y. Chapple V. Roberts P. Matson P. Prevalence, consequence, and significance of reverse cleavage by human embryos viewed with the use of the Embryoscope time-lapse video system.Fertil Steril. 2014; 102: 1295-1300.e2Abstract Full Text Full Text PDF PubMed Scopus (109) Google Scholar). Other abnormal phenotypes discernible from TLM include absent cleavage in the presence of karyokinesis, chaotic cleavage, and cell lysis, all of which jeopardize implantation potential (23Barrie A. Homburg R. McDowell G. Brown J. Kingsland C. Troup S. Preliminary investigation of the prevalence and implantation potential of abnormal embryonic phenotypes assessed using time-lapse imaging.Reprod Biomed Online. 2017; 34: 455-462Abstract Full Text Full Text PDF PubMed Scopus (36) Google Scholar). Incorporation of TLM in embryo assessment thus allows for identification of embryos with the best developmental parameters while allowing for the deselection of embryos exhibiting events which negatively impact competence, thereby maximizing potential for single embryo transfer and live-birth (24Castello D. Motato Y. Basile N. Remohi J. Espejo-Catena M. Meseguer M. How much have we learned from time-lapse in clinical IVF?.Mol Hum Reprod. 2016; 22: 719-727Crossref PubMed Scopus (27) Google Scholar). No, we concede that existing studies do not unequivocally prove that time-lapse has improved outcomes. Neither, however, is there equally strong data to conclude that it hasn't–existing studies have demonstrated inherent flaws that need to be acknowledged. Retrospective studies have reported higher live birth rates using TLM, however these studies have been limited by methodologic flaws, such as the comparison of low oxygen tension TLM culture vs. atmospheric oxygen tension in controls, as well as the use of different culture media in study groups (25Fishel S. Campbell A. Montgomery S. Smith R. Nice L. Duffy S. et al.Live births after embryo selection using morphokinetics versus conventional morphology: a retrospective analysis.Reprod Biomed Online. 2017; 35: 407-416Abstract Full Text Full Text PDF PubMed Scopus (33) Google Scholar, 26Barrie A. Homburg R. McDowell G. Brown J. Kingsland C. Troup S. Embryos cultured in a time-lapse system result in superior treatment outcomes: a strict matched pair analysis.Hum Fertil (Camb). 2017; 20: 179-185Crossref PubMed Scopus (7) Google Scholar). Still, such data have demonstrated a benefit that is consistent with our own internal experience involving the exclusive use of the EmbryoScope TLM system (Vitrolife) (27Zaninovic N. Zhan Q. Rosenwaks Z. Time-lapse implementation in a clinical setting: outcome results.in: Meseguer M. Time-lapse microscopy in in vitro fertilization. Cambridge University Press, Cambridge2016: 144-164Google Scholar). On the whole, the bulk of retrospective data concluding no benefit of TLM has suffered from methodologic flaws and has failed to fully harness the data provided by TLM systems. For instance, the retrospective cohort from Mumusoglu et al. (28Mumusoglu S. Yarali I. Bozdag G. Ozdemir P. Polat M. Sokmensuer L.K. et al.Time-lapse morphokinetic assessment has low to moderate ability to predict euploidy when patient- and ovarian stimulation-related factors are taken into account with the use of clustered data analysis.Fertil Steril. 2017; 107: 413-421.e4Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar) concluding low ability to predict euploidy in 103 consecutive IVF patients did not examine multinucleation, DUCs, or embryo fragmentation, instead focusing only on morphokinetic assessment. The pilot randomized controlled trial (RCT) published by Kaser et al. (29Kaser D.J. Bormann C.L. Missmer S.A. Farland L.V. Ginsburg E.S. Racowsky C. A pilot randomized controlled trial of day 3 single embryo transfer with adjunctive time-lapse selection versus day 5 single embryo transfer with or without adjunctive time-lapse selection.Hum Reprod. 2017; 32: 1598-1603Crossref PubMed Scopus (29) Google Scholar) concluded that adjunctive use of the Eeva test did not improve clinical pregnancy rate per transfer (29Kaser D.J. Bormann C.L. Missmer S.A. Farland L.V. Ginsburg E.S. Racowsky C. A pilot randomized controlled trial of day 3 single embryo transfer with adjunctive time-lapse selection versus day 5 single embryo transfer with or without adjunctive time-lapse selection.Hum Reprod. 2017; 32: 1598-1603Crossref PubMed Scopus (29) Google Scholar). However, this study compared day 3 single embryo transfer with Eeva test to day 5 single embryo transfer with conventional assessment alone, but did not compare day 3 transfer with or without Eeva. Eeva was not designed to select embryos on day 5, the study was prematurely terminated, and it was underpowered to detect statistically significant differences. Our experience with the Eeva algorithm is that it employs too few parameters to correctly evaluate embryos and once DUCs are excluded from the database, which Eeva low identifies, no significant differences between Eeva groups are found. For objective comparison of TLM systems, it is crucial to recognize that not all systems work equally well and that generalized criticism of TLM needs to take into the account the specific TLM system being employed and algorithms used. The RCT by Goodman et al. (30Goodman L.R. Goldberg J. Falcone T. Austin C. Desai N. Does the addition of time-lapse morphokinetics in the selection of embryos for transfer improve pregnancy rates? A randomized controlled trial.Fertil Steril. 2016; 105: 275-285.e10Abstract Full Text Full Text PDF PubMed Scopus (120) Google Scholar) also concluded that analysis of morphokinetic parameters did not lead to improved outcomes; strength of this study was that both test and control embryos were incubated in TLM incubators, thus addressing a fundamental limitation of prior studies (30Goodman L.R. Goldberg J. Falcone T. Austin C. Desai N. Does the addition of time-lapse morphokinetics in the selection of embryos for transfer improve pregnancy rates? A randomized controlled trial.Fertil Steril. 2016; 105: 275-285.e10Abstract Full Text Full Text PDF PubMed Scopus (120) Google Scholar). However, more than three-fourths of patients in both groups underwent blastocyst transfer, with an average of 2 blastocysts transferred and an average patient age of 33 years. The favorable demographics of this population are not representative of most clinical practices and the preponderance of blastocyst transfer limits analysis of cleavage stage evaluation. Even with these limitations, clinical pregnancy rates with TLM were 5.2% higher overall and 6.3% higher in patients under 40 years. The authors concluded that TLM did not significantly improve reproductive outcome, however the study was only powered to detect a minimum difference of 10% between groups. Conventional evaluation detected only 5.4% of multinucleated embryos, which was noted to be independently associated with 49% decreased implantation (odds ratio [OR] 0.51; 95% confidence interval [CI] 0.30–0.86; P=.01). Moreover, the morphokinetic score was positively associated with implantation. -Whereas early meta-analyses concluded no clinical benefit to the use of TLM, the most recent meta-analysis from 2017 suggests a higher clinical pregnancy rate (51.0% vs. 39.9%) and increased live birth rate (44.2% vs. 31.3%) when 5 RCTs examining 1,637 patients are analyzed (31Pribenszky C. Nilselid A.M. Montag M. Time-lapse culture with morphokinetic embryo selection improves pregnancy and live birth chances and reduces early pregnancy loss: a meta-analysis.Reprod Biomed Online. 2017; 35: 511-520Abstract Full Text Full Text PDF PubMed Scopus (106) Google Scholar, 32Racowsky C. Kovacs P. Martins W.P. A critical appraisal of time-lapse imaging for embryo selection: where are we and where do we need to go?.J Assist Reprod Genet. 2015; 32: 1025-1030Crossref PubMed Scopus (66) Google Scholar). While the relative quality of the evidence is admittedly moderate owing to significant inconsistencies across studies, strength of this meta-analysis was the inclusion of the most patients to date as well as the exclusion of two studies that employed TLM devices but continued to evaluate embryos according to conventional, single time point criteria (33Park H. Bergh C. Selleskog U. Thurin-Kjellberg A. Lundin K. No benefit of culturing embryos in a closed system compared with a conventional incubator in terms of number of good quality embryos: results from an RCT.Hum Reprod. 2015; 30: 268-275Crossref PubMed Scopus (43) Google Scholar, 34Wu Y.G. Lazzaroni-Tealdi E. Wang Q. Zhang L. Barad D.H. Kushnir V.A. et al.Different effectiveness of closed embryo culture system with time-lapse imaging (EmbryoScopeTM) in comparison to standard manual embryology in good and poor prognosis patients: a prospectively randomized pilot study.Reprod Biol Endocrinol. 2016; 14: 49Crossref PubMed Scopus (30) Google Scholar). Yes, we believe this is a reasonable conclusion but perhaps not for all programs. The relative benefit of TLM will be lost on most programs exclusively performing PGS and significantly reduced in those programs focused purely on blastocyst transfer. Even for such programs, TLM evaluation can help in selecting the top euploid embryos for frozen embryo transfer (35Irani M. Reichman D. Robles A. Melnick A. Davis O. Zaninovic N. et al.Morphologic grading of euploid blastocysts influences implantation and ongoing pregnancy rates.Fertil Steril. 2017; 107: 664-670Abstract Full Text Full Text PDF PubMed Scopus (87) Google Scholar). On the other hand, for those practices evaluating embryos on day 3 for potential transfer versus extended culture (as the literature would support), and for whom PGS is not viewed as a panacea (it isn't), the maximal benefit of TLM can be leveraged, making use of undisturbed culture, identification of abnormal cleavage dynamics (i.e., DUCs), and analysis of morphokinetic parameters. Indeed, the study by Adamson et al. (36Adamson G.D. Abusief M.E. Palao L. Witmer J. Palao L.M. Gvakharia M. Improved implantation rates of day 3 embryo transfers with the use of an automated time-lapse-enabled test to aid in embryo selection.Fertil Steril. 2016; 105: 369-375.e6Abstract Full Text Full Text PDF PubMed Scopus (65) Google Scholar) is one of the few studies to directly compare day 3 embryo transfers using a TLM system against day 3 transfers with conventional morphology analysis alone, and demonstrated significantly higher implantation and clinical pregnancy rates in the test group compared with controls. Nearly perfect appearing 8-cell embryos on day 3 may have attained that fate via the perils of DUCs or other abnormal developmental milestones, and we know that such embryos exhibit a marked reduction in blastulation and implantation. It would be naïve to think that identification of such abnormal developmental parameters cannot lead to more optimal selection of embryos for cleavage stage transfer. If TLM improves embryo development, improves embryo selection, and ultimately reduces times to pregnancy by improving outcomes, then yes. Secondary advantages are savings in time, not having to enter the laboratory for embryo evaluation, decreased production costs, and reduced use of culture media, dishes, mineral oil, and gases. Fewer culture dishes and slides are required per patient (16 embryos per slide for example in the EmbryoScope [Vitrolife]) and the same slides can be used throughout development, changing culture medium when needed (37Aparicio B. Cruz M. Meseguer M. Is morphokinetic analysis the answer?.Reprod Biomed Online. 2013; 27: 654-663Abstract Full Text Full Text PDF PubMed Scopus (55) Google Scholar). Such systems, while associated with an initial increase in overhead costs, allow for streamlined laboratory workflows and ultimately we believe will be widely adopted. While TLM has already demonstrated great utility, we still need to define the value of this technology for individual patient populations. All patients will benefit from undisturbed reduced oxygen culture conditions and by identifying embryologic factors which are clearly associated with negative embryo outcomes. Young patients with high embryo yield who are excellent candidates for blastocyst transfer may benefit less from nuanced analysis of TLM parameters as compared to poorer prognosis patients who have either failed prior cycles, failed to reach the blastocyst stage, or who are older. Indeed, the greatest benefits of this technology may well be found in such populations—further, well-executed studies are needed. Catherine Racowsky, Ph.D.View Large Image Figure ViewerDownload Hi-res image Download (PPT) The ability to select which embryo has the highest implantation potential remains one of the greatest challenges in the management of IVF patients, as this knowledge would shorten the duration and burden of treatment and make it safer with increasing elective single embryo transfer. One of the more recent touted advancements in the field of embryo evaluation has been the introduction of continuous time-lapse imaging. Time-lapse imaging is not a new technology and has been effectively used in a variety of applications ranging from the timing of crop harvesting to monitoring success of anti-wrinkle face creams. Of note, it was first used in our field 20 years ago for imaging human oocytes (38Payne D. Flaherty S.P. Barry M.F. Matthews C.D. Preliminary observations on polar body extrusion and pronuclear formation in human oocytes using time-lapse video cinematography.Hum Reprod. 1997; 12: 532-541Crossref PubMed Scopus (323) Google Scholar); however, only in the last decade has the technology received considerable attention as a potential adjunct to conventional morphological assessment for embryo evaluation. The overarching question is whether there is a physiologic basis for the application of this technology. Is there a range of times during which an embryo progresses through the various developmental milestones that predicts implantation and pregnancy outcomes? On a grander scheme, the medical field has monitored developmental milestones in humans for centuries. A baby usually gives its first social smile at 6 weeks of age, sits unassisted by 6 months, and walks at a year. However, if that baby first walks at 10 months or 16 months does that have long-term implications since he or she did, in fact, reach the milestone albeit perhaps sooner or later than the so-called "average"? Therefore, the primary focus of this exploration of early developmental milestones has been to determine which deviations from the norm have deleterious consequences and which variations are benign. Conventional approaches for assessing developmental competence of the embryo employs, at a minimum, static morphological evaluation immediately before embryo transfer and may also involve similar daily evaluations. The addition of continuous time-lapse footage not only has allowed such evaluations to occur during uninterrupted culture, but also has enabled comparisons of the timing of cell divisions, and developmental milestones among a cohort of embryos. Furthermore, time-lapse enables embryologists to observe exquisitely time-sensitive dysmorphic events such as multinucleation, direct, uneven, and reverse cleavage. Continuous visualization of embryo development, and documentation of developmental phenomena not previously described in detail, has laid the groundwork for the current time-lapse movement, which has been focused on identifying specific markers in development that have predictive potential. A number of commercially available time-lapse systems have hit the market and early retrospective and observational studies evaluating the safety have proved that these closed, benchtop incubators provide adequate and stable culture conditions. There are only a limited number of randomized control trials to date evaluating whether use of time-lapse imaging improves embryo selection compared with conventional morphology (30Goodman L.R. Goldberg J. Falcone T. Austin C. Desai N. Does the addition of time-lapse morphokinetics in the selection of embryos for transfer improve pregnancy rates? A randomized controlled trial.Fertil Steril. 2016; 105: 275-285.e10Abstract Full Text Full Text PDF PubMed Scopus (120) Google Scholar, 33Park H. Bergh C. Selleskog U. Thurin-Kjellberg A. Lundin K. No benefit of culturing embryos in a closed system compared with a conventional incubator in terms of number of good quality embryos: results from an RCT.Hum Reprod. 2015; 30: 268-275Crossref PubMed Scopus (43) Google Scholar, 34Wu Y.G. Lazzaroni-Tealdi E. Wang Q. Zhang L. Barad D.H. Kushnir V.A. et al.Different effectiveness of closed embryo culture system with time-lapse imaging (EmbryoScopeTM) in comparison to standard manual embryology in good and poor prognosis patients: a prospectively randomized pilot study.Reprod Biol Endocrinol. 2016; 14: 49Crossref PubMed Scopus (30) Google Scholar, 39Rubio I. Galán A. Larreategui Z. Ayerdi F. Bellver J. Herrero J. et al.Clinical validation of embryo culture and selection by morphokinetic analysis: a randomized, controlled trial of the EmbryoScope.Fertil Steril. 2014; 102: 1287-1294Abstract Full Text Full Text PDF PubMed Scopus (219) Google Scholar, 40Kirkegaard K. Hindkjaer J.J. Grøndahl M.L. Kesmodel U.S. Ingerslev H.J. A randomized clinical trial comparing embryo culture in a conventional incubator with a time-lapse incubator.J Assist Reprod Genet. 2012; 29: 565-572Crossref PubMed Scopus (108) Google Scholar, 41Matyas S.Z. Kovacs P. Forgacs V. Sajgo A. Pribenszky C.S. Selection of single blastocyst for transfer using time-lapse monitoring during in vitro fertilization in good prognosis patients: a randomized controlled trial.Hum Reprod. 2015; 30: i119Google Scholar, 42Kahraman S. Cetinkaya M. Pirkevi C. Yelke H. Kumtepe Y. Comparison of blastocyst development and cycle outcome in patients with eSET using either conventional or time lapse incubators. A prospective study of good prognosis patients.J Reprod Stem Cell Biotechnol. 2013; 3: 55-61Crossref Google Scholar, 43Cruz M. Gadea B. Garrido N. Pedersen K.S. Martínez M. Pérez-Cano I. et al.Embryo quality, blastocyst and ongoing pregnancy rates in oocyte donation patients whose embryos were monitored by time-lapse imaging.J Assist Reprod Genet. 2011; 28: 569-573Crossref PubMed Scopus (158) Google Scholar). Moreover, the studies are heterogeneous with varied patient populations, control groups, incubators, culture conditions, and outcomes. Only one study has been carried out to evaluate live-birth rates (39Rubio I. Galán A. Larreategui Z. Ayerdi F. Bellver J. Herrero J. et al.Clinical validation of embryo culture and selection by morphokinetic analysis: a randomized, controlled trial of the EmbryoScope.Fertil Steril. 2014; 102: 1287-1294Abstract Full Text Full Text PDF PubMed Scopus (219) Google Scholar). Most studies compared blastocyst development or clinical pregnancy rates between traditional large box incubators and the closed time-lapse imaging systems, clouding the relative contributions of the incubator versis continuous imaging per se. Embryo selection criteria for the majority of the studies are not well defined, and additional confounding factors are many, including day of transfer (day 3 vs. 5), number of embryos transferred, fresh or frozen embryo use, oocyte source (autologous vs. donor), and type of time-lapse system. Finally, many of the RCTs have excluded poor prognosis patients, and no studies have been performed to evaluate the different time-lapse incubators head-to-head with bright field vs. dark field imaging or single well culture vs. group culture. Despite the considerable variability among studies, a common theme among them is small sample size. Consequently, there have been systematic reviews and meta-analyses attempting to pool the data (44Armstrong S. Arroll N. Cree L.M. Jordan V. Farquhar C. Time-lapse system for embryo incubation and assessment in assisted reproduction.Cochrane Database Syst Rev. 2015; : CD011320PubMed Google Scholar, 45Chen M. Wei S. Hu J. Yuan J. Liu F. Does time-lapse imaging have favorable results for embryo incubation and selection compared with conventional methods in clinical in vitro fertilization? A meta-analysis and systematic review of randomized controlled trials.PLoS One. 2017; 12: e0178720PubMed Google Scholar, 46Racowsky C. Martins W.P. Effectiveness and safety of time-lapse imaging for embryo culture and selection: it is still too early for any conclusions?.Fertil Steril. 2017; 108: 450-452Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar, 47Kaser D.J. Racowsky C. Clinical outcomes following selection of human preimplantation embryos with time-lapse monitoring: a systematic review.Hum Reprod Update. 2014; 20: 617-631Crossref PubMed Scopus (8) Google Scholar). A Cochrane review from 2015 pooled 994 patients from three RCTs and concluded that there was insufficient evidence to support benefit from time-lapse imaging (44Armstrong S. Arroll N. Cree L.M. Jordan V. Farquhar C. Time-lapse system for embryo incubation and assessment in assisted reproduction.Cochrane Database Syst Rev. 2015; : CD011320PubMed Google Scholar). Chen et al. (45Chen M. Wei S. Hu J. Yuan J. Liu F. Does time-lapse imaging have favorable results for embryo incubation and selection compared with conventional methods in clinical in vitro fertilization? A meta-analysis and systematic review of randomized controlled trials.PLoS One. 2017; 12: e0178720PubMed Google Scholar) performed a meta-analysis of 10 RCTs including 4 employing oocyte randomization and 6 randomizing patients. For those studies with oocyte randomization, including a total of 1154 embryos, there was no difference in the primary outcome of blastocyst rate (RR 1.08; 95% CI 0.94–1.25). Pooled analysis of ongoing pregnancy rate in the studies randomizing women (including 1403 subjects) again showed no difference between conventional and time-lapse imaging groups (RR 1.04; 95% CI 0.80–1.36). And just recently, pooled data from Racowsky and Martins (46Racowsky C. Martins W.P. Effectiveness and safety of time-lapse imaging for embryo culture and selection: it is still too early for any conclusions?.Fertil Steril. 2017; 108: 450-452Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar) attempting to minimize heterogeneity by segregating studies with similar comparison groups and outcomes, again showed no significant benefit (RR 1.02; 95% CI 0.85–1.22) (Fig. 1). As mentioned previously, all the meta-analyses and systemic reviews have stressed heterogeneities among studies. In addition, there appears to be a substantial amount of bias as it is difficult to blind all parties involved in studies of this nature and the unpredictability of embryo development can lead to high patient dropout. Furthermore, if there is low embryo yield, embryo selection is reduced and time-lapse may be of even less utility. Although the one study evaluating live birth as the primary outcome did report a statistically significant increase in live birth with time-lapse imaging, it is worth noting that this study has been reported to have high risk for bias in many of these reviews. It is the overwhelming conclusion among the published systematic reviews that there is a paucity of homogenous and unbiased data to conclude with any certainty that time-lapse offers an advantage over conventional morphological assessment for embryo evaluation and selection. Without concrete data that time-lapse is superior to conventional morphological grading, one must evaluate the cost of such technology to inquire if this is cost-effective in a busy IVF laboratory. To date, there are no published cost-analyses comparing conventional incubation to time-lapse systems. The cost of the equipment itself is impressive, equaling up to six figures, in addition to a staggering annual service contract, albeit one that is optional. The time spent viewing and annotating the embryos equals, if not exceeds, the time saved by not removing the embryos to view under the microscope. In addition, using the set focal planes of the time-lapse system hinders the embryologist's ability to scroll through the embryo in real time, which may require additional training and time. There is thus an additional inherent cost for an IVF laboratory to use the technology, which we feel is inappropriate to pass on to patients without more definitive evidence of benefit to them. Of note, a recent survey revealed that of 35 laboratories in the United States that have a time-lapse system, 7 (28%) charge patients for use of the system (48Dolinko A.V. Farland L.V. Kaser D.J. Missmer S.A. Racowsky C. National survey on use of time-lapse imaging systems in IVF laboratories.J Assist Reprod Genet. 2017; 34: 1167-1172Crossref PubMed Scopus (16) Google Scholar) IVF is one of the most dynamic and rapidly evolving fields of medicine. It is essential that we explore and embrace new technologies to allow us to provide the best possible care to our patients. However, we must do so with due diligence to validate emerging technology to ensure it provides reproducible benefit to patients in a cost-effective manner. At this point in time, available data do not support time-lapse imaging as being superior or economical compared to conventional embryo culture and assessment. In our view, the technology is now early on the incline of the "slope of enlightenment" in the Gartner hype innovation cycle (Fig. 2). We look forward to future large, robust appropriately designed RCTs, which either prove or disprove a benefit of this technology for embryo evaluation and selection.