From the present to the future in the IVF lab

Published 08 June 2022

ESHRE’s second Campus meeting with ‘live’ participants post-lockdown was organised by the SIG Embryology. The three-day event pursued the analogy of ‘haute cuisine’ in the techniques, skills and service of the IVF laboratory.

ESHRE’s SIG Embryology has long been marked by its high membership and effervescent activity, and nowhere was that enthusiasm better seen than at a May Campus meeting in Barcelona. The themes of the meeting took a detailed look at the IVF lab of today – design, incubators, labelling and witnessing, fertilisation, culture media, embryo biopsy, microinjection and cryopreservation – but there was also much looking ahead, to labs in which machine learning might resolve the puzzles of embryo selection, where computer vision might identify patterns of cell viability presently invisible to human observation, or where processes left to the vagaries of different techniques would be made consistent and efficient under the direction of artificial intelligence. Carlos Simon, opening his presentation on translational science for tomorrow’s embryology, said: ‘Everything in the IVF lab is a process, and all processes can be automated.’

Laura Rienzi, from GeneraLife in Italy, in reviewing the huge contribution made by oocyte vitrification to the lives of so many people, also looked ahead in her closing remarks to automated vitrification, which will, she said, ensure ‘the quality of the process’ by standardising timings, volumes and procedures. ‘We should aim at standardisation and automation,’ she said, ‘but we are not there yet.’ Nevertheless, the technology of vitrification has already ‘completely changed’ the reach of the IVF lab, with ‘an incredible impact on everyday life’. Oocyte vitrification is not an ‘add-on’, insisted Rienzi, but now has a crucial role in fertility treatment in its safety potential (segmentation, single embryo transfer) and application (egg banking for egg donation, fertility preservation in cancer patients). A 2016 systematic review led by Rienzi found that vitrification is superior to slow-freezing in terms of clinical outcomes and cryosurvival for oocytes, cleavage-stage embryos and blastocysts.(1)

The other ‘game changer’ in the IVF lab has been time-lapse technology, but Kersti Lundin, a former co-ordinator of the SIG Embryology (and a past Chair of ESHRE), was not yet convinced of its benefits for patients, even if recognising its benefits for the clinic. The latter included an improved culture environment, easier embryo handling, improved logistics in the lab, and real-time visualisation of embryo development with automated embryo assessment (and hopefully scoring). However, echoing the conclusions of an ESHRE good practice recommendation for the use of time-lapse, Lundin reiterated that ‘a clear clinical benefit’ as reflected in improved success rates ‘remains to be proven’.(2) A recently published RCT from Lundin and colleagues found no significantly different ongoing pregnancy rate between a time-lapse and morphology control group.(3) But, like Rienzi, Lundin too looked ahead to the improvements in time-lapse which machine learning might bring to embryo scoring and selection – but so far, she conceded, ‘the technology is not performing better than the embryologists’.

The title of this Campus meeting pursued the analogy of embryology as the ‘haute cuisine’ of the IVF lab, where aspirations stretched to a Michelin star (not beyond reach in Barcelona where, said local alumnus Pedro Barri, there are 49 restaurants with at least one Michelin star). So we had ‘basic ingredients’ too, but it was somewhat salutary to hear that the assessment of both oocyte and sperm quality were still far from ideal, particularly the latter.

But first Lisbon embryologist Carlos Plancha outlined what we can still be sure of in oocyte quality. Female gamete quality, he explained, is the main determinant of embryo developmental competence, which is acquired with progressive folliculogenesis – and which might be estimated from cumulative LBR data (‘the most clinically relevant measure of ART success’). Although this estimate does not provide information on individual oocyte quality, said Plancha, ‘it may uncover relevant information for embryologists and clinicians’. However, some basic questions on oocyte quality remain unanswered, not least the number of oocytes needed for live birth according to patient age. Oocyte vitrification seems not to affect cumulative LBR as long as sufficient oocytes are available. Prospective assessment of oocyte quality may presently be achieved by three methods, all of which have question marks: morphology; genomic or proteomic assessment; or machine learning (‘which may minimise subjectivity’ but still needs validation).

The question of sperm selection seems even more problematic, according to Dundee andrologist Chris Barratt, who described the knowledge base of male infertility as ‘quite low’. Presently, he argued, sperm selection is based mainly on morphology and motility, which, he noted, fails to recognise the complexity of the sperm cell – and thus ‘we still don’t know how to select the best cell’. Of course, there has been ‘fascinating’ progress in the biology of male infertility, notably in the role of phospholipase C zeta in calcium release and egg activation, but application in the clinic remains elusive. Similarly, in diagnosis. Oxidative stress, for example, is subject to non-consensus about the assays, or the prescription of antioxidants. So, said Barratt, ‘if we don’t know how to diagnose oxidative stress, how can we treat it?’. To resolve such uncertainties and lack of progress in male reproductive health, he called for renewed collaborations and, of course, better dedicated funding. ‘What we’re doing now is not working,’ he said, ‘and there is a great need for high quality progress.’

Benchmarking progress, however, was implicit in a presentation by Andrea Borini from GeneraLife in Italy which reviewed the thorny debate over treatment outcomes in Europe and the USA. It’s a long story which began in 2006 with a US assertion that results were inferior in Europe largely because of reimbursement and state-funding. This was countered from Europe that the difference was largely explained by transfer policies reflected in ‘aggressive stimulation’ and higher rates of twins and multiples in the US. Since then, said Borini, US policy – with the strong support of CDC and ASRM recommendations on single embryo transfer – has become much more aligned with Europe (eSET, milder stimulation) although availability remains less, private centres dominate the landscape, and costs are much higher ($12,000 plus cost of drugs).

Among the many advances described in the IVF lab were systems designed to avoid errors, such as mismatching and non-conformance. Martine Nijs from Cooper Surgical estimated that each oocyte/embryo is ‘manipulated’ some 20 times on its journey from pick-up to transfer. Serious adverse events, as described in the Council of Europe’s 2019 guide to the quality and safety of tissues and cells for human application, include mix-up of sperm samples, wrongly fertilised oocytes, insemination with samples from the wrong donor and labelling errors.(4) Despite the few cases reported, however, their consequences can be catastrophic – for both patents and the clinic. Presently, said Nijs, ‘double-checking by a second operator (manual witnessing) is the main control measure used to avoid biological sample misidentification’, but this has the potential drawbacks of human error. This may, she proposed, be eliminated by electronic witnessing, a system which creates a unique identifier for each patient based on barcode or radiofrequency identification. Such systems, said Nijs, ensure traceability and record each witnessing step, tracking samples in and out of storage and checking if each is approved for transfer. The benefits, she added, were multiple in terms of security and lab efficiency.

Underlying many of the presentations on the working of the IVF lab were ESHRE’s revised guidelines for good practice in IVF laboratories which, in its several sections, covers many of the topics raised at this Campus meeting – albeit from a 2015 perspective.(5) No doubt, with such landscape changes in the lab as time-lapse and vitrification, this too is due an update. But coming in development from ESHRE are good practice recommendations on how to deal with errors in ART, recommendations on the number of embryos to transfer in IVF/ICSI, add-ons in IVF, and very soon, with stakeholder review now completed, a full guideline on mosaicism in PGT.

1. Rienzi L, Gracia C, Maggiulli R, et al. Oocyte, embryo and blastocyst cryopreservation in ART: systematic review and meta-analysis comparing slow-freezing versus vitrification to produce evidence for the development of global guidance. Hum Reprod Update 2016; 23: 139-155.
2. ESHRE working group on time-lapse technology. Good practice recommendations for the use of time-lapse technology. Hum Reprod Open 2020; 19: hoaa008.
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5. ESHRE Guideline Group on Good Practice in IVF Labs. Revised guidelines for good practice in IVF laboratories (2015). Hum Reprod 2016; 31: 685–686.

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