Clinical validation of an automatic classification algorithm applied on cleavage stage embryos: analysis for blastulation, euploidy, implantation, and live-birth potential

STUDY QUESTION

Is a commercially available embryo assessment algorithm for early embryo evaluation based on the automatic annotation of morphokinetic timings a useful tool for embryo selection in IVF cycles?

SUMMARY ANSWER

The classification provided by the algorithm was shown to be significantly predictive, especially when combined with conventional morphological evaluation, for development to blastocyst, implantation, and live birth, but not for euploidy.

WHAT IS KNOWN ALREADY

The gold standard for embryo selection is still morphological evaluation conducted by embryologists. Since the introduction of time-lapse technology to embryo culture, many algorithms for embryo selection have been developed based on embryo morphokinetics, providing complementary information to morphological evaluation. However, manual annotations of developmental events and application of algorithms can be time-consuming and subjective processes. The introduction of automation to morphokinetic annotations is a promising approach that can potentially reduce subjectivity in the embryo selection process and improve the workflow in IVF laboratories.

STUDY DESIGN, SIZE, DURATION

This observational, retrospective cohort study was performed in a single IVF clinic between 2018 and 2021 and included 3736 embryos from oocyte donation cycles (423 cycles) and 1291 embryos from autologous cycles with preimplantation genetic testing for aneuploidies (PGT-A, 185 cycles). Embryos were classified on Day 3 with a score from 1 (best) to 5 (worst) by the automatic embryo assessment algorithm. The performance of the embryo classification model for blastocyst development, implantation, live birth, and euploidy prediction was assessed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All embryos were monitored by a time-lapse system with an automatic cell-tracking and embryo assessment software during culture. The embryo assessment algorithm was applied on Day 3, resulting in embryo classification from 1 to 5 (from highest to lowest developmental potential) depending on four parameters: P2 (t3-t2), P3 (t4-t3), oocyte age, and number of cells. There were 959 embryos selected for transfer on Day 5 or 6 based on conventional morphological evaluation. The blastocyst development, implantation, live birth, and euploidy rates (for embryos subjected to PGT-A) were compared between the different scores. The correlation of the algorithm scoring with the occurrence of those outcomes was quantified by generalized estimating equations (GEEs). Finally, the performance of the GEE model using the embryo assessment algorithm as the predictor was compared to that using conventional morphological evaluation, as well as to a model using a combination of both classification systems.

MAIN RESULTS AND THE ROLE OF CHANCE

The blastocyst rate was higher with lower the scores generated by the embryo assessment algorithm. A GEE model confirmed the positive association between lower embryo score and higher odds of blastulation (odds ratio (OR) (1 vs 5 score) = 15.849; P < 0.001). This association was consistent in both oocyte donation and autologous embryos subjected to PGT-A. The automatic embryo classification results were also statistically associated with implantation and live birth. The OR of Score 1 vs 5 was 2.920 (95% CI 1.440-5.925; P = 0.003; E = 2.81) for implantation and 3.317 (95% CI 1.615-6.814; P = 0.001; E = 3.04) for live birth. However, this association was not found in embryos subjected to PGT-A. The highest performance was achieved when combining the automatic embryo scoring and traditional morphological classification (AUC for implantation potential = 0.629; AUC for live-birth potential = 0.636). Again, no association was found between the embryo classification and euploidy status in embryos subjected to PGT-A (OR (1 vs 5) = 0.755 (95% CI 0.255-0.981); P = 0.489; E = 1.57).

LIMITATIONS, REASONS FOR CAUTION

The retrospective nature of this study may be a reason for caution, although the large sample size reinforced the ability of the model for embryo selection.

WIDER IMPLICATIONS OF THE FINDINGS

Time-lapse technology with automated embryo assessment can be used together with conventional morphological evaluation to increase the accuracy of embryo selection process and improve the success rates of assisted reproduction cycles. To our knowledge, this is the largest embryo dataset analysed with this embryo assessment algorithm.

STUDY FUNDING/COMPETING INTEREST(S)

This research was supported by Agencia Valenciana de Innovació and European Social Fund (ACIF/2019/264 and CIBEFP/2021/13). In the last 5 years, M.M. received speaker fees from Vitrolife, Merck, Ferring, Gideon Richter, Angelini, and Theramex, and B.A.-R. received speaker fees from Merck. The remaining authors have no competing interests to declare.

TRIAL REGISTRATION NUMBER

N/A.

P-213 Assisted Hatching as new indication to improve diminished implantation potential after spontaneous collapsed blastocyst

Study question

To demonstrate whether assisted hatching (AH) could improve reproductive outcome of collapsed blastocysts (CB). Pregnancy rate (PR) and the implantation rate (IR) were studied.

Summary answer

Our results demonstrate an indication of AH for collapsed blastocyst. The AH could reverse or minimize the negative impact of the collapse on implantation.

What is known already

With the introduction of the time-lapse thecnology, different aspects of the embryonic development are analyzed in detail. According to Marcos et al., 2015, the incidence of spontaneous blastocyst collapse is 19% and decreases the implantation potential from 48.5% to 35.1%. Recently, Sciorio et al., 2020 described significantly higher IR of 61.2% and OPR of 53.7% when blastocysts which had not collapsed were replaced compared to cycles in which collapsed blastocysts were transferred (IR rate 22.6% and OPR 17.7%). This study suggests that human collapsed blastocysts are less likely to implant and generate a pregnancy compared with embryos that do not.

Study design, size, duration

Retrospective study performing AH routinely in warmed embryos for 5 years in 4 groups: study groups CB (No-AH /CB- AH) and control groups NCB (No-AH / NCB-AH). To find out if the differences between the study groups were due solely to the effect of AH, we introduced two additional contemporary control groups NCB with and without HA. SET (single embryo transfer) was performed. IR and PR were analyzed and compared using the Chi-square test.

Participants/materials, setting, methods

A total of 754 blastocysts distributed in 4 groups were analyzed: 188 CB without AH (No-AH), 161 CB with AH, 199 NCB No-AH and 206 NCB with AH. All blastocysts were warmed embryos and the collapse was identified retrospectively in a time-lapse system before warming. The AH was performed by laser (removing 1/4 part of the ZP) after warming the embryos.

Main results and the role of chance

Comparing the clinical PR between embryos with or without collapse a significant adverse effect was confirmed by the collapse (CB 47.6% 166/349 vs NCB 60.5% 245/405) p &lt; 0.001. The same trend was observed in the ongoing PR (OPR),(CB 30.7% 107/349 vs NCB 40.2% 163/405, p = 0.006). Regarding the AH effect, and considering all warmed embryos (regardless if they were affected by collapse or not) we did not find any improvement in the PR and IR when we performed AH on the blastocysts. For PR: No-AH: 53.2% 206/387 vs AH: 55.9% 205/367, p = 0.469 and for IR: No-AH: 42.6% 165/387 vs AH: 47.7% 175/367, p = 0.164. Focussing solely on warmed blastocyst which collapsed, and performing AH, we encountered significant differences regarding OPR (No-AH 25.5% 48/188 vs AH 36.6% 59/161, p = 0.025). When selecting only day 5 embryos the same effect was observed (No-AH 25.8% 40/155 vs 37.9% 47/124, p = 0.03).

Limitations, reasons for caution

The collapse was described as ≥ 50% of the surface of the trophectoderm being separated from the ZP regardless how far the trophectoderm cells are apart from the ZP. Some blastocysts suffer a strong collapse reducing considerably the size of the embryo, but in others the collapse is quite subtle.

Wider implications of the findings

Our results demonstrate a real indication for AH in CB. It would be interesting to incorporate continuous embryo monitoring in laboratories to identify collapse to ensure AH and improving results. Maybe these events of collapse would imply an additional metabolic stress which may affect viability or displacing the implantation window.

Trial registration number

not applicable

P-629 A prospective, randomized, placebo-controlled pilot trial investigating telomere length dynamics and ovarian function in patients with diminished ovarian reserve (DOR) after danazol treatment

Study question

Could the administration of a synthetic steroid -danazol- for 3 months reactivate telomerase activity and lengthen telomeres in patients with DOR?

Summary answer

Danazol treatment resulted in an increase of the mean leukocyte telomeric length (TL) but did not improve fertility results after the nearest ovarian stimulation (OS).

What is known already

A primary molecular cause of aging is telomere attrition, given that the accumulation of critically short telomeres leads organ dysfunction. Telomere shortening can be counteracted by the telomerase enzyme, which is responsible for adding deoxyribonucleotides to the linear ends of chromosomes. In patients with DOR, TL in granulosa cells (GCs) is short and telomerase activity is absent, compromising their proliferative capacity. Previuos studies have shown that estrogens can activate telomerase gene transcription through estrogen-responsive elements located in the promoter of the telomerase gene. Therefore, telomere attrition could be reduced in patients with DOR upon telomerase reactivation.

Study design, size, duration

This blinded, placebo-controlled pilot trial was carried out at IVIRMA Madrid clinic between February 2020 and February 2022. The study included 12 patients with DOR (AMH&lt;2ng/ml) which were randomized to danazol or placebo. Patients had 12 visits for health supervision and in vitro fertilization (IVF) treatment. Both groups received danazol (400mg per day) or placebo for 3 months. As control group, 7 patients with normal ovarian reserve (AMH≥2ng/ml) were included.

Participants/materials, setting, methods

In both groups, blood samples were collected prior (PT) and after the treatment (AT). Luteinized GCs and blood samples were obtained during oocyte retrieval, after OS. Leukocytes were purified in Ficoll gradients and then, evaluated for TL and TRF1 levels by Quantitative Fluorescent in Situ Hybridization followed by image acquisition using high resolution confocal microscope. IVF parameters were assessed according to IVIRMA standard protocols.

Main results and the role of chance

A total of 19 women were recruited: 5 in the placebo group (39.8±2.7 years), 7 in Danazol group (41.0±3.0 years) and 7 in control group (39.5±3.0 years). The Danazol group showed a trend to higher mean TL in leukocytes after the treatment (108.2±37.4 versus 99±13.2 a.u., AT vs PT). Interestingly, the percentage of long telomeres also increased with treatment (15.5±0.0 versus 10.8±8.1 a.u., AT vs PT). In addition, there was a decrease of the percentage of critically short telomeres (15.7±0.0 versus 20.8±9.9 a.u. AT vs PT). In the placebo group, mean leukocyte TL and the percentage of long and short telomeres remained constant. These findings suggest that telomeres lengthen after Danazol treatment. The protein levels of TRF1, a shelterin involved in telomere protection, were similar in both Danazol and placebo groups. Regarding fertility, there were no differences in the number of antral follicles, total and MII oocytes, fertilization rate and blastocyst formation. The control group had, as expected, signficantly higher mean follicle number after OS when compared with Danazol (16.0±1.4 and 0.7±0.9, P &lt; 0.0001) and placebo (16.0±1.4 and 5.0±3.8, p = 0.0127) groups, and higher numbers of total oocytes retrieved (p = 0.006; control and Danazol, and p = 0.007; control and placebo).

Limitations, reasons for caution

Firstly, the number of patients included in the study is limited due to strict inclusion/exclusion criteria. Secondly, because follicle growth can take up to 150 days, danazol effects could be noticeable at later OS and not only in the first OS, which was the only one studied here.

Wider implications of the findings

Since telomeres seem to elongate in blood samples after Danazol treatment in DOR patients, we could hypothesize that this may have a positive impact for general health, including the ovaries. Thus, danazol therapy might help improving IVF outcomes, perhaps at later OS.

Trial registration number

NCT04058678

O-138 Covid-19 vaccine does not affect sustained implantation rates after single euploid embryo transfer, a retrospective study with 4868 cases

Study question

Is sustained implantation rate (SIR) of covid-19 vaccinated women diminished in assisted reproduction treatments due to endometrial receptivity harm?

Summary answer

SIR of euploid embryos remains constant regardless vaccination and doses applied, but impact of interval last dose-embryo transfer needs to be further evaluated.

What is known already

Little is known about the effects of both covid infection and vaccines on endometrial receptivity of women attempting motherhood.

There is a generalized concern about potential secondary effects of covid vaccine on many health areas, and assisted reproduction is not an exception. Then, it is mandatory on the current epidemic context to evaluate if either infection or its preventive treatment may interfere reproductive physiology of infertile patients.

ART offers a robust model to study this problem by controlling oocyte and embryo quality with the use of PGT-A, then enabling the study of endometrial independent contribution to reproductive success.

Study design, size, duration

Retrospective study analyzing two cohorts, historical cohort of PGT-A cases using own oocytes one year pre-pandemia, and post vaccination initiation from women already having received one or two doses.

Patients undergoing single embryo transfers (ET) after PGT-A were included, to be able to discern purely endometrial factors of sustained implantation. Means and proportions with their corresponding 95%CI (within brackets) were calculated, and crude/adjusted odds ratios calculated for the main outcomes, SIR and clinical pregnancy rate (CPR)

Participants/materials, setting, methods

A total of 4868 ET were included on this study, 3272 for the control, non vaccinated group, vs 890 from women already vaccinated with at last one dose at the time of ET.

The main outcomes were CPR per embryo transfer (presence of a sac by ultrasonography on week 7th), and SIR (fetal heartbeat at week 12th). Crude and adjusted odds ratio were calculated, using logistic regression models to control for potentially confounding variables.

Main results and the role of chance

Mean age was 38.3 years 95%CI(38.2-38.4), BMI, 23.2kg/m2 95%CI(23.1 23.4), fresh oocytes on 80%, mixed 16.4% and vitrified on 3.6% of cases. Donor sperm used on 12.8% of treatments, and testicular retrieved sperm on 2.5% of them. Day of embryo transfer was D5 on 71.3%  and D6 on 28.6% cases.

CPR per ET was 70.6% 95%CI(69.3-71.9) in the control group and 70.4%95%CI(67.4-73.4) on vaccinated, OR 0.994 95%CI(0.849-1.163), and after adjustment by patient’s age, oocyte age, source of sperm, donor sperm use, day of ET, use of vitrified oocytes and BMI, AdjOR 1.039 95%CI(0.876-1.233), while SIR in the controls was 64.3% 95%CI(62.7-66.0) vs. 62.6% 95%CI(58.8-66.4) on vaccinated, with OR 0.929 95%CI(0.777-1.110) and AdjOR 0.981 95%CI(0.807-1.192), p &gt; 0.05.

Those patients having received only one dose or two doses by the time of ET, showed comparable results, on both CPR and SIR.

Concerning data categorized per time quartiles (from vaccine to ET), while CPR was comparable, SIR, on the first  quartile (Q1) was 66.5%, while Q2 was 68.0%, Q3 66.3%, and Q4 50.4%, and using Q1 as reference, ORQ2-Q1 1.073 95%CI(0.680-1.693), ORQ3-Q1 0.869 95%CI(0.545-1.385) and OR Q4-Q1 0.512 95%CI(0.321-0.818), p = 0.009 while after adjustment AdjORQ2-Q1 0.965 95%CI(0.585-1.594), AdjORQ3-Q1 0.834 95%CI(0.492-1.413) and AdjORQ4-Q1 0.533 95%CI(0.316-0.899), p = 0.018.

Limitations, reasons for caution

This is a retrospective study, and although controlled statistically, possible biases due to the nature of the work remain possible, and a cause-effect link cannot be purely drawn from it. Further prospective studies on the potential effect of covid vaccines on reproductive outcomes are still needed.

Wider implications of the findings

Our results send a message of reassurance to patients in the process of assisted reproductive treatment regarding the potential negative impact of the vaccine on endometrial receptivity and reproductive outcomes. Aiming motherhood is no reason for delaying vaccination against covid-19.

Trial registration number

Not applicable

P-208 Embryo assessment at the click of a button is now possible: evaluation of a deep-learning algorithm integrated directly with the time-lapse platform

Study question

Is the embryo scoring function based on deep learning of specific time-lapse systems clinically useful for classifying human blastocyst?

Summary answer

Blastocyst grading according to iDAScore® is directly associated with conventional morphology and implantation potential, at least in treatments without preimplantation genetic testing for aneuploidy (PGT-A).

What is known already

The conventional approach of embryo evaluation in the time-lapse systems is for embryologists to manually annotate a number of morphological and/or morphokinetic parameters. These values are then used in models of clinical outcome prediction. Embryo selection can be automated by using artificial intelligence (AI) to predict morphokinetic and morphology parameters. In this case, AI is employed in an indirect way to optimize the daily workflow based on existing traditional parameters. Finally, the most innovative approach is the use of AI to directly predict pregnancy, implantation or even live birth by using only time-lapse images.

Study design, size, duration

A retrospective cohort study including 518 patients who underwent IVF treatments and whose embryos (n = 3,406) were cultured in EmbryoScope Plus® time-lapse systems. Blastocysts were routinely evaluated by senior embryologists according to the ASEBIR morphological criteria. Then, embryos were scored using the iDAScore algorithm whose values range from 1 to 9.9.

Participants/materials, setting, methods

Embryo evaluation was performed automatically by iDAScore with the use of deep learning and a neural network. The algorithm was developed considering the entire embryo development to rank embryos according to likelihood of implantation. Embryo score was compared with conventional morphological quality, euploidy rate and the subsequent implantation outcome of 567 single blastocyst transfers. Then, we quantified the contribution of the automatic embryo score to implantation with multivariate logistic regression analysis in different patient populations.

Main results and the role of chance

The comparison between the embryo score provided by the iDAScore and the morphological category (A, B, C or D) assigned by embryologists showed a direct association*. The mean and standard deviation was 9.2 ± 0.4 for A; 8.2 ± 1.2 for B; 6.9 ± 1.6 for C and 4.0 ± 1.8 for D. The euploidy rate increased when embryos showed higher automatic scores*: 45.9% for score ≤ 8.0 (n = 354), 55.6% for score 8.1-8.8 (n = 169) and 62.8% for score &gt;8.8 (n = 180). The implantation rate increased as the embryo score improved*: 37.8% for score ≤ 7.8 (n = 127), 50.9% for score 7.9-8.9 (n = 163), 65.7% for score &gt;8.9 (n = 277). The logistic regression analysis of iDAScore took into account possible confounding factors: oocyte origin (donated vs. autologous); type of embryo transfer (fresh vs. frozen); oocyte age; patient body mass index; PGT-A (tested vs. non-tested embryos) and day of embryo transfer (fifth vs. sixth day of embryo development). iDAScore value was related to the odds of implantation in the oocyte donation program (OR = 1.61; 95%CI [1.19-2.19]; p &lt; 0.001; n = 265) and in conventional treatments with autologous oocytes (OR = 1.52; 95%CI [1.22-1.90]; p &lt; 0.001; n = 192). There was no significant association of embryo score with implantation in treatments involving PGT-A (n = 110).

*p&lt;.05

Limitations, reasons for caution

This study is limited by its retrospective nature. The single-center design should be taken into account when considering the universal application of the model. Although our clinic was not involved in the development of iDAScore, and therefore this study should be considered as an external validation.

Wider implications of the findings

Our findings confirm that embryo evaluation can be performed automatically allowing embryologists to utilize their time more efficiently in other tasks of the IVF process that are more complex and require high precision and attention.

Trial registration number

This research has been funded by a grant from The Ministry of Science, Innovation and Universities FIS (PI21/00283) awarded to M.M.

P-168 Does the concentration of Interleukin-6 (IL-6) in spent embryo culture medium tell us anything? Association with implantation potential after euploid embryo transfer

Study question

Could Interleukin-6 (IL-6) secretion by euploid embryos provide extra information in the prediction of clinical outcomes after human blastocyst transfer?

Summary answer

The concentration of IL-6 in the spent embryo culture medium provides additional and non-redundant information associated with the success of a euploid embryo transfer.

What is known already

Previous studies revealed that the concentration of IL-6 in the culture medium could be useful in selecting the embryo for implantation (Dominguez et al., 2015) and higher concentrations of IL-6 was reported in embryos that reach blastocyst stage than in arrested ones (Lindgren et al., 2018). Recently, proteomic information gained from the analysis of the embryonic secretome have been used to predict the potential of a euploid embryo to lead to a live birth (Bori et al., 2021). Out of 92 proteins measured, IL-6 was one of the most relevant for the prediction of live birth along with blastocyst morphology.

Study design, size, duration

This prospective study included 157 euploid embryos from the preimplantation genetic testing for aneuploidies (PGT-A) program. Embryos were cultured until the blastocyst stage in EmbryoScope systems with single-step medium (Gems, Genea). All of them were routinely assessed by senior embryologists. Morphological quality was based on ASEBIR criteria and morphokinetic parameters were automatically annotated by guided annotations tool. The spent culture medium was collected on day 5/6 of embryo development (day of trophectoderm biopsy).

Participants/materials, setting, methods

Chromosome analysis was performed using next-generation sequence technology. In parallel, 20 µL of spent culture medium from each blastocyst was analyzed with Human IL-6 ELISA Kit. Only euploid embryos were used in the following analysis. We examined the association between IL-6 levels (pg/ul) and embryo morphology and morphokinetics. Out of the total, 77 embryos were selected and transferred according to ASEBIR morphological quality. Pregnancy, implantation and live birth rate were correlated to IL-6 concentration.

Main results and the role of chance

The average concentration of IL-6 in spent embryo culture medium was 1.76±0.93 pg/ul. The protein value was not related to embryo morphology (p = 0.332): 2.35±1.60 pg/ul for embryos graded as A; 1.72±0.95 pg/ul for embryos graded as B and 1.79±0.76 pg/ul for embryos graded as C. Likewise, IL-6 level was not related to morphokinetic parameters. Division time to 2 cells, 3 cells, 4 cells, 5 cells and time to blastulation were not statistically different among the following quartiles of IL-6: ≤ 1.06 pg/ul (n = 41), from 1.07 to 1.66 pg/ul (n = 39), from 1.67 to 2.21 pg/ul (n = 40) and &gt;2.21 pg/ul (n = 37). However, the concentration of IL-6 was higher in those euploid embryos that achieved a clinical pregnancy than in those embryos that failed after transfer. For spent culture media with less than 1.66 pg/ul of IL-6, pregnancy rate was 50%*, implantation rate was 50%* and live birth rate 43.80%. For spent culture media with more than 1.66 pg/ul of IL-6, pregnancy rate was 77.80% *, implantation rate was 75,60%* and live birth rate was 64.40%. *p&lt;0.05

Limitations, reasons for caution

The detection limit in protein quantification and the specific culture medium used that may affect IL-6 concentrations are the main limitations of our study.

Wider implications of the findings

Our findings demonstrated that the concentration of IL-6 in spent culture medium is independent of embryo morphology and morphokinetics, but it is related to the success of a PGT-A treatment. This may provide a promising approach to predict implantation after euploid embryo transfer by measuring the IL-6 protein.

Trial registration number

CDTI (IDI-20191102)

P-228 Higher oxidation levels in follicular fluid correlate with better outcome in ICSI treatments

Study question

Can the oxidative status of the follicular fluid be a valid biomarker of the quality of the oocyte cohort and clinical outcome in ICSI treatments?

Summary answer

The follicular fluid (FF) of oocyte cohorts that achieved at least one pregnancy, ongoing pregnancy and life birth have higher oxidative stress levels.

What is known already

The role of oxidative stress in female infertility is yet unclear, due to the numerous factors that participate in the production and activity of reactive oxygen species (ROS), and the different techniques used for its detection. The Fertissimo TCL AnalyzerTM (Carmel Diagnostics, Israel) uses thermochemiluminiscence to assess the oxidative status (OS) of biological samples by counting the photons emitted per second (cps) after a heat-catalyzed oxidative reaction. Using this technique, a negative correlation was found between ROS levels in FF and patient age (Wiener-Megnazi et al, 2004), but its potential as a biomarker of clinical outcome is unclear.

Study design, size, duration

Prospective observational study performed in a single IVF center during one year. 173 women were subjected to controlled ovarian stimulation as part of an autologous (103 patients) or ovum donation ICSI treatment (70 donors). The OS of the follicular fluid (FF) obtained in the oocyte retrieval was assessed and compared with the characteristics of the treatment and clinical outcome.

Participants/materials, setting, methods

The first tube of follicular fluid obtained in the oocyte retrieval was centrifuged (10 minutes at 600g) and the supernatant was analyzed in the Fertissimo TCL AnalyzerTM. OS results were normalized per volume and summarized as TCL-Score (average photon counting from 50-280s) and Ratio (slope of the reaction time curve). TCL parameters were compared with the demographics, number of oocytes retrieved and clinical outcome of the cohort using Pearsons Correlation and Anova tests

Main results and the role of chance

FF from donors had higher TCL-Score (44.27±14.41cps vs 40.59±11.65cps, P = 0.066) and Ratio (367.38±89.47 vs 329.88±78.12, P = 0.004) than patients. A significant inverse correlation was found between TCL Ratio and the age of the women (Pearsons Correlation Coefficient (PCC)=-0.207; P = 0.006). A direct significant correlation was found between the body mass index (BMI) and the TCL-Score (PCC=0.186, P = 0.014) and Ratio (PCC=0.186, P = 0.014). TCL-Score (PCC=0.173, P = 0.023) and Ratio (PCC= 0.275, P  &lt;0.001) also had a significant positive correlation with the number of mature oocytes retrieved. In donors, TCL Ratio was negatively correlated with the fertilization rate (PCC=-0.350, P = 0.009) and positively correlated with the blastocyst formation rate at day 5 (PCC=0.289, P = 0.032), but said correlation was not found in FF of patients (PCC(Ratio-Fertilization rate)=0.066, P = 0.554; PCC(Ratio- Blastocyst rate)=-0.005, P = 0.965). However, in patients, a statistically significant negative correlation was found between TCL-Score and the good quality blastocyst rate (PCC=-0.234, P = 0.038), which was not statistically significant in donors (PCC=-0.131, P = 0.342). Finally, TCL Ratio levels resulted significantly higher in FF of oocyte cohorts that resulted in at least one pregnancy (362.77±86.60 vs 321.90±77.60, P = 0.005), one ongoing pregnancy (365.99±84.10 vs 322.66±80.94, P = 0.003) and one life birth (364.93±83.74 vs 330.07±84.17, P = 0.017).

Limitations, reasons for caution

Some miscalibration issues were met in the course of the analysis, which may hinder its reproducibility. Stimulation protocol or sperm quality was not considered in the analysis. A larger scale, controlled trial should be performed to validate results.

Wider implications of the findings

Presented results are in tune with previously published data using similar and different techniques for assessing oxidative and antioxidative capacity in FF samples. The analysis of the oxidative status of the FF could be a valid biomarker of clinical outcome of ICSI treatments and as indicator for antioxidant therapy.

Trial registration number

APOTIP/2020/015 Generalitat Valenciana.

P-224 The sex of the human embryos affects the oxidation profile of the spent culture media

Study question

Is the oxidative status of the spent culture media used in ICSI treatments related to embryo sex and newborn characteristics?

Summary answer

Female embryos produce higher levels of oxidative stress in the culture media than male embryos.

What is known already

Sex-associated differences in embryo development have previously been observed. Studies suggest that male embryos have a faster pre-implantation development, higher morphological grading and lower glucose consumption (Nasiri et al, 2018). The thermochemiluminiscence (TCL) assay quantifies the oxidative status of biological samples by catalyzing an oxidative reaction through heating and counting the photons emitted per second. TCL parameters are directly correlated to the content of oxidant agents in the sample. Previous analysis used TCL assay to relate higher oxidative metabolism in embryos with higher viability. Analysis of spent culture media with TCL could be a potential biomarker for embryo sex prediction.

Study design, size, duration

Prospective observational study over 86 transferred blastocysts (all single embryo transfer) that reached life-birth, belonging to ICSI treatments, including autologous and oocyte donation, performed in a single fertility clinic during three consecutive years. The oxidative status of the spent culture media was analyzed and compared with the characteristics of the newborns.

Participants/materials, setting, methods

Embryo cohorts were cultured in individual wells in an Embryoscope incubator, using single-step Gems culture media (Genea Biomedx). The best embryo of the cohort was selected for transfer using morphologic (ASEBIR) and morphokinetic criteria (KID Score algorithmTM, Vitrolife, (KS)). Spent culture media was analyzed in the Fertissimo TCL Analyzer (Carmel Diagnostics, Israel) and oxidation parameters were compared with the sex, weight and height of the newborns through ANOVA, C2 and Pearsons Correlation coefficient (PCC) tests.

Main results and the role of chance

The sex ratio of the embryos (male to female) resulted 59.3%. The sex ratio was increasingly higher the better morphological classification: C = 16.7%, B = 56.0%, A: 73.3%. KS did not give significantly different scores to the embryos depending on their sex: average KS (female)=6.78 vs average KS (male)=7.03, P = 0.621. No correlation was found between KS or the morphological classification and the weight and height of the babies: PCC (KS-height)=0.158, P = 0.349; PCC (KS-weight)=0.082, P = 0.569; average newborn height: C = 51.67±1.15cm, B = 50.57±3.48cm, A = 50.92±1.95cm, P = 0.791, average newborn weight: C = 3,386.00±459.11g, B = 3,283.35±658.12g, A = 3,229.07±732.13g, P = 0.877. TCL ratio (slope of the time curve of photon emission, representing the level of oxidant agents in the sample) was statistically significantly higher in the culture media of female embryos than of male embryos: Ratio (female)=119.54±13.37 vs Ratio (male)=111.62±15.80, P = 0.017. No statistically significant difference was found in the TCL Ratio between the three morphological classes, although the tendency of the data is towards lower levels with increasing morphological classification: Ratio (C)=120.40±14.43, ratio (B)=116.32±14.39 and ratio (A)=111.27±16.62, P = 0.237. No correlation was found between the TCL parameters and the weight and height of the newborn: PCC (Ratio-height)=-0.173, P = 0.198; PCC (Ratio-weight) 0.036, P = 0.753.

Limitations, reasons for caution

Patient demographics, habits and male sperm characteristics were not considered for the analysis, but might impact embryo characteristics and intrauterine development of the fetus. A larger scale study should be performed to validate results.

Wider implications of the findings

The differential oxidative load embryos exert over the culture medium might be related to a glucose consumption-associated sex dimorphism. Measuring the oxidative status of the culture medium could serve as a non-invasive biomarker for embryo sex selection. This technique could be an interesting option in carriers of sex-linked diseases.

Trial registration number

not applicable

O-004 The bias is out of the bag: IVF culture dish well number influences embryo selection decision-making and implantation outcome

Study question

Is there a selection bias against embryos placed in higher-numbered wells inside a multi-well IVF culture dish. Does this selection bias alone impact implantation outcomes?

Summary answer

Top-quality embryos present in higher-numbered wells are statistically less likely to be selected for transfer, independent of any differences in quality or development between wells.

What is known already

Substantial intra-and inter-observer variability in embryo selection, as well as differences in quality assessment and laboratory environment, have been shown to affect IVF success. Currently many clinics have adopted stringent guidelines to control for human errors and workflow variation. Still, the impact of errors in laboratory and medical procedures was reported as high as 12%. This is particularly relevant for the IVF lab, where high workload and stress influence rate of errors and patient outcome. This groundbreaking study emphasizes how cognitive tendencies are inherent to the embryo selection process.

Study design, size, duration

This study used a retrospective dataset from three highly experienced fertility clinics (1 US and 2 European clinics). A total of 4,275 Fresh IVF cycles were analyzed. For each treatment cycle, embryo quality grades, corresponding embryo well numbers, day 5 selection and implantation outcomes were documented. All cycles were performed using the EmbryoSlide 12-well culture dish and a time-lapse system. All three datasets were analyzed separately and also combined.

Participants/materials, setting, methods

For each dataset, three analyses were conducted: (1) total number of selected embryos were calculated for each corresponding well number; (II) the proportion of implanted embryos, relative to the total number of selected embryos, were quantified to calculate the “success rate” for each well number; (II) the distribution of top-quality embryos between wells were quantified and compared. Results were normalized by total number of transferred embryos and IVF implantation success rates reported for each clinic.

Main results and the role of chance

A negative trend was found between well number, ranging from 1-12, and number of embryos selected for transfer. This trend was significant (p &lt; 0.05) and occurred independently in each dataset. Odds ratios (OR) for the relation between selecting embryos for transfer from wells 1-5, and from 8-12 = Clinic A: 2.16, Clinic B: 1.78, Clinic C: 2.45. Alternative hypotheses were tested: (1) top-quality embryos are clustered in lower-numbered wells during culture; (2) enhanced embryo quality and conditions are found in lower-numbered wells, which should manifest in higher rates of implantation. Results for each clinic showed a statistically even distribution of top-quality embryos between wells (within 2 standard deviations from the mean; not significant), yet ‘success rate’ for transferred embryos increased by well number (by 12-30% between wells 1-5 and wells 8-12; OR = 1.19, 1.06, 1.08 for Clinic A, B, and C, respectively). An inverse trend existed between an embryo’s likelihood of being selected for transfer, and its likelihood of implanting. We conclude that embryologists may tend to select the first acceptable embryo for transfer. Embryos from higher-numbered wells were significantly more likely to implant, since they overcame this bias when equitably evaluated and selected for transfer.

Limitations, reasons for caution

Though our findings were significant, they need to be repeated on larger datasets with more inter-centre variation, and key embryo culture and outcome variables recorded.

Wider implications of the findings

This study emphasizes the inherent human error that exists inside IVF clinics. Machine learning systems that reduce human bias and increase objective standardization, even if they are not inherently better than embryologists, would improve implantation rates. Future studies should be directed toward AI based technologies that can accomplish this.

Trial registration number

Not Applicable

P-277 An artificial intelligence (AI) deselection model for top-quality blastocysts: algorithmic analysis of morphokinetic features for aneuploidy may increase implantation rates

Study question

Can an AI deselection model identify distinct morphokinetic patterns in top-quality blastocyst with unknown ploidy that fail to implant?

Summary answer

An AI based deselection model was able to predict implantation failure based on morphokinetic features previously found to associate with aneuploidy.

What is known already

Aneuploidy is the most common explanation for implantation failure of high-quality blastocysts. Yet, high-quality blastocysts with unknown ploidy that fail to implant are often morphologically indistinguishable from blastocysts that succeed to implant. Our previously published results (ESHRE 2021) demonstrated that aneuploid blastocysts were more likely to reach development events (t2-t8) later, and that the timing between each event was statistically longer (p &lt; 0.001), when compared to euploid embryos. Given that delayed morphokinetic rates are tightly linked to ploidy, we investigated whether similar known morphokinetic features were associated with implantation failure in top-graded embryos.

Study design, size, duration

Time-lapse sequences of 3,259 top-quality blastocysts from fresh single embryo transfer cycles with known implantation outcomes were analyzed using an AI-based algorithm. The algorithm utilized convolutional neural network extracted temporal features based on multiple morphokinetic parameters known to associate with ploidy.

Participants/materials, setting, methods

time-lapse sequences and morphokinetic events were algorithmically analyzed to measure the rate of mitotic division events and compare the number of embryos in each category (implanted/nonimplanted) that reached each developmental event at least one standard deviation (SD) later than the mean for implanted embryos.

Main results and the role of chance

Results showed statistical differences in the following morphokinetic features between the two categories: t2, t3, t4, and t3-t4 (p &lt; 0.05). Implanted top-graded blastocysts were likely to reach t2, t3, and t4 after 25.23 ± 3.8 SD, 36.06 ± 3.4 SD, and 37.14 hours ±3.6 SD, respectively. The time gap between t3 and t4 was found to be 12.25 hours ± 5.31 SD. Given this, we followed the methodology described above to propose cutoff values (in hours) that differentiated between non-implanted and implanted top-graded blastocysts based on their morphokinetic profiles. Implantation failure was found to be associated with the likelihood of reaching t2 after 28.61 hours (OR = 2.36, CI 0.96-5.77), t3 after 39.46 (OR = 3.48, CI 1.62-7.47), and t4 after 40.79 hours (OR = 2.23, CI 1.09- 4.53). A time gap between t3 and t4 of more than 17.56 hours was also associated with implantation failure (OR = 2.48, CI 1.12-5.48), indicating perturbed mitotic activity. The cutoff values proposed here were incorporated into the algorithm for optimized deselection of morphologically similar top-quality blastocysts with delayed morphokinetic profiles.

Limitations, reasons for caution

This study needs to be validated on a larger, multi-centric dataset that takes into account more morphokinetic features associated with ploidy in order to increase the robustness of our algorithm.

Wider implications of the findings

For the first time, our algorithmic model proposed here demonstrates the utility of an AI tool to deselect top-graded blastocysts that would otherwise be selected for transfer based on conventional morphologic assessment alone.

Trial registration number

Not Applicable

O-176 End-to-end deep learning system for recognition of euploid and aneuploid embryos using time-lapse videos

Study question

Can an Artificial Intelligence (AI) system based on a deep learning algorithm analyze time-lapse videos for ploidy status prediction?

Summary answer

Our spatiotemporal model can distinguish aneuploid embryos from euploid embryos using time-lapse videos from 10 to 115 hours post-insemination (hpi) with an accuracy of 71,28%.

What is known already

As the maternal age advances chances of aneuploidy in oocyte also increases and there is a high chance of early termination of pregnancy. Pre-implantation genetic testing for aneuploidy (PGT-A) is a reliable tool for detecting chromosomal status. However, PGT-A is an invasive technique in which protocol requires an embryo biopsy. Continuous monitoring of embryo development led to AI models for the prediction of ploidy based on blastocyst images or morphokinetic parameters. Previous publications showed that euploid embryos reach blastulation earlier than non-euploid embryos. This is the first attempt to predict ploidy by analyzing continuous embryo development through captured time-lapse images.

Study design, size, duration

The present study consisted of a single-center retrospective analysis for the evaluation of ploidy status with a non-invasive method. We developed our models based on a balanced dataset of 940 videos (from 10 to 115 hpi) extracted from the EmbryoScope time-lapse system. All the videos were divided into 90% for training and validating and 10% for testing. The target class for the predicted models was the results of PGT-A on blastocyst by next-generation sequencing.

Participants/materials, setting, methods

We used an end-to-end approach to develop an automated AI system capable of extracting features from images and classifying them considering temporal dependencies. First, a convolutional neural network (CNN) extracted the most relevant features from each frame. We used a deep architecture known as ResNet50.  Second, a bidirectional long short-term memory (LSTM) layer received this information and analyzed temporal dependencies, obtaining a low-dimensional feature vector that defined each video. Finally, a multilayer perceptron classified them.

Main results and the role of chance

Euploid and aneuploid precision was 69% and 75%, respectively. Euploid and aneuploid sensitivity was 79% and 64%, respectively. Euploid and aneuploid F1 score was 73% and 69% respectively. The global accuracy associated with our spatiotemporal model to differentiate between the two classes achieved 71,28% on this dataset. Additionally, we trained models with external information such as maternal age (38,3±3,9 versus 39,1±3,1), but the performance did not improve. Note that we did not apply a prior selection of good quality videos to study more reliably the possible inclusion of an AI model for chromosomal status analysis in clinical practice. 

Limitations, reasons for caution

The main limitation of this study is the single-center retrospective approach and the reduced size of the database, therefore future prospective research would improve model performance. However, the preliminary results showed the high potential of the methods.

Wider implications of the findings

Our results showed potential automation of chromosomic status evaluation. Our findings led to a possible non-invasive method and the research of new unknown key factors for determining ploidy. Further studies with a large number of time-lapse videos could result in a potential translation to clinical use.

Trial registration number

not applicable

P–203 Applying artificial intelligence for ploidy prediction: The concentration of IL–6 in spent culture medium, blastocyst morphological grade and embryo morphokinetics as variables under consideration

Study question

Would it be possible to predict embryo ploidy by taking into account conventional morphological and morphokinetic parameters together with IL–6 concentration in spent culture medium?

Summary answer

Our artificial neural network (ANN) trained with blastocyst morphology, embryo morphokinetics and IL–6 concentration distinguished between euploid/aneuploid embryos in 65% of the testing dataset.

What is known already

The analysis of spent embryo culture media represents the protein and metabolic state of the embryo and could be a non-invasive method of obtaining information about embryo quality. The impact of the presence/absence of several proteins in embryo culture samples over clinical results has been widely studied. The IL–6 is one of the most mentioned protein for its effect on embryo development, implantation and likelihood of achieving a live birth. In this initial attempt, we examined the predictive value for euploidy of a model that took into account the concentration of IL–6 in the spent culture medium.

Study design, size, duration

This prospective study included 319 embryos with PGT-A results. Out of the total, 127 were euploid and 192 aneuploid embryos. Concentration of IL–6 in spent embryo culture media (collected on the day of trophectoderm biopsy-fifth/sixth day of development), morphokinetic parameters (division time to 2 cells-t2; to 3 cells-t3, to 4 cells-t4; to 5 cells-t5 and time of blastocyst formation-tB) and blastocyst morphological grade (according to ASEBIR criteria) were considered to predict the embryo ploidy.

Participants/materials, setting, methods

Embryos were cultured in EmbryoScope. The chromosome analysis was performed using next-generation sequence technology. The concentration of IL–6 was measured in 20µL of spent embryo culture media with ELISA kits. Morphokinetic parameters were automatically annotated and the blastocyst morphology was evaluated by senior embryologists based on blastocele expansion, inner cell mass and trophectoderm quality. All the embryos were divided into 70% for training, 15% for validating and 15% for testing our ANN model with MatLab®.

Main results and the role of chance

The general description for the euploid embryo population was the following: 2% of the embryos were graded as A, 71% were graded as B and 28% were graded as C; the means and standard deviations were 25.32±2.97 hours (h) for t2, 35.33±5.15h for t3, 37.30±5.43h for t4, 48.24±6.62h for t5 and 103.93±12.8h for tB; and the average of IL–6 concentration was 1.51±0.70 pg/ml. The general description for the aneuploid embryo population was the following: 1% of the embryos were graded as A, 48% were graded as B and 51% were graded as C; the means and standard deviations were 26.13±3.51h for t2, 36.70±4.29h for t3, 38.20±4.24h for t4, 49.86±6.89h for t5 and 107.10±8.29h for tB; and the average of IL–6 concentration was 1.47±0.71 pg/ml. Our ANN model showed a higher general success rate as we increased the variables considered in the final prediction of euploid embryos. The accuracy, sensitivity and specificity for the testing dataset were: 0.60, 0.12 and 0.87 with morphokinetic parameters; 0.63, 0.24 and 0.93 with morphokinetics and IL–6 concentration; and 0.65, 0.16 and 0.96 with morphokinetics, IL–6 concentration and blastocyst morphological grade.

Limitations, reasons for caution

The low sensitivity and high specificity achieved in our models indicated that they were more capable of detecting aneuploid than euploid embryos. As this was a preliminary study, the small number of embryos included in the test (n = 48) was also a limitation.

Wider implications of the findings: The results showed that our model tended to classify the embryos as aneuploid. More euploid embryos would be necessary to train our model and achieve better results in the prediction of chromosomally normal embryos. Further studies with large number of embryos and additional variables could improve the non-invasive ploidy prediction.

Trial registration number

Not applicable

O-214 Undisturbed embryo culture under High Humidity atmosphere in a time-lapse system increases pregnancy rates

Study question

Does culture in high relative humidity conditions (HC) improve pregnancy rates when using a time-lapse system (TLS) and single-step (SS) culture medium?

Summary answer

Using an integrated-TLS and SS medium, culture under HC increases the likelihood of embryos to achieve a pregnancy with respect to those cultured in DC.

What is known already

Many variables affect embryo development, and need to be precisely tuned in every IVF laboratory, especially inside the incubators. TLS provide stability during embryo culture, which is a well-known key factor for a proper embryo development. The humidity content of culture atmosphere is especially relevant in order to avoid oscillations in culture media osmolality. It has been previously reported that culture under HC has a significant effect on embryo quality and morphokinetics. However, studies assessing the effect of HC in clinical outcome are rare and inconclusive, mostly due to the variability in the incubator device used and insufficient sample size.

Study design, size, duration

The present is a retrospective study performed over 1624 ICSI treatments from 3 fertility clinics from December 2017 to October 2020. Zygote cohorts were randomly assigned to dry (N = 794) or humid conditions (N = 830). It includes autologous treatments with (N = 555) and without (N = 368) pre-implantation genetic testing (PGT) and egg donation treatments (N = 701). Following selection by combining morphological and morphokinetic criteria, 1611 mostly single embryo transfers (92%) were performed, 779 from DC and 832 from HC.

Participants/materials, setting, methods

Stimulation, oocyte pickup and fertilization were performed according to the standard procedures of the clinic. We used a GERI incubator (Genea Biomedx), with 6 separated chambers for individual patients, 3 of them configured to work in DC, and 3 in HC. Embryos were cultured in specific 16-well GERI trays with single-step Gems® culture medium (Genea Biomedx). The effect of HC in pregnancy rate was assessed by multivariate logistic regression and Pearson Chi Square Test.

Main results and the role of chance

Types of treatment and patient demographics were homogeneously distributed in the two study groups. Mean patient age was 39.88±4.47 years, BMI: 23.54±4.21 Kg/m2 and number of correctly fertilized oocytes: 7.86±3.87. A logistic regression was performed, including other possible affecting factors: ovum age and origin, transfer day, fresh or frozen-warmed embryo transfer, number of transferred embryos and the use of PGT. Said analysis revealed that embryos cultured in HC are more likely to achieve a pregnancy than those cultured in DC (OR = 1.30, 95% CI (1.05-1.59), p=0.014). Pregnancy rate was significantly higher in HC (66.7%) than in DC (60.9%) in the total embryo transfers (p = 0.017). Pregnancy rate was also higher in HC in fresh embryo transfers (68.6% in HC vs 63.2% in DC; p = 0.133) and frozen-thawed transfers (65.2% in HC vs 59.1% in DC; p = 0.062), although differences were not statistically significant due to the reduced sample size. Stratifying the results, the significant difference remained in transfers belonging to autologous cycles (68.4% HC vs 56.5% in DC; p = 0.030) and in treatments in which PGT was performed (67.1% HC vs 56.0% in DC; p = 0.023), but the difference in egg donation procedures was not statistically significant (66.4% in HC vs 64.7% in DC, p = 0.577).

Limitations, reasons for caution

This is a retrospective analysis performed over the clinics’ treatments, so it might be compromised by some bias, although multivariable analysis may overcome them. For further assessing the effect of HC in clinical results a prospective controlled study, with a larger sample size could be performed, also comparing life-birth rates.

Wider implications of the findings

These results, alongside our previous findings (Valera et al. 2020, Albert et al. 2020), support that HC contributes to optimize embryo development and clinical results in undisturbed culture in TLS with single-step medium. To our knowledge, this is the largest study on the matter and the first performing multivariable analysis.

Trial registration number

Not applicable

O-084 Computer vision can distinguish between euploid and aneuploid embryos. A novel artificial intelligence (AI) approach to measure cell division activity associated with chromosomal status

Study question

Can we distinguish between top-grade euploid and aneuploid embryos by AI measurement of cell edges in time-lapse videos?

Summary answer

Aneuploid embryos can be distinguished from euploid embryos by AI determination of a longer time to blastulation and higher cell activity.

What is known already

Continuous monitoring of the embryo development has brought out morphokinetic parameters that are used to predict pre-implantation genetic testing (PGT) results. Previous publications showed that euploid embryos reach blastulation earlier than non-euploid embryos. However, time-lapse data are currently under-utilized in making predictions about embryo chromosomal content. AI and computer vision could take advantage of the massive amount of data embedded in the images of embryo development. This is the first attempt to distinguish between euploid and aneuploid embryos by computer vision in an objective and indirect way based on the measurement of cell edges as a proxy for cell activity.

Study design, size, duration

We performed a retrospective analysis of 1,314 time-lapse videos from embryos cultured to the blastocyst stage with PGT results. This single-center study involved two phases; a comparison of the start time of blastulation between euploid (n = 544) and aneuploid embryos (n = 797). In phase two, we designed a novel methodology to examine whether precise measurement of cell edges over time could reflect cell activity differences in blastulation.

Participants/materials, setting, methods

We assumed that the delay in blastulation is reflected by higher cell activity that could be determined accurately for the first time using computer vision and machine learning to measure the length of the edges (from t2 to t8). We compared computer vision based measurements of cell edges, reflecting cell number and size, in videos of 231 top-grade euploid (n = 111) and aneuploid (n = 120) embryos.

Main results and the role of chance

The mean and standard deviation of blastulation start time was 100.1±6.8 h for euploid embryos and 101.8±8.2 h for aneuploid embryos (p &lt; 0.001). Regarding the measurement of cell activity, a computer vision algorithm identified the edges and provided a certainty score for each edge, higher when the algorithm is more certain that this is a cell edge (as opposed to noise in the images). A threshold was set to distinguish cell edges from noise using this score. The following results for top-grade embryos are shown as the sum of the edge lengths (µm) average of 160 pictures per embryo (frames between t2 and t8). The total length of the cell edges increased from two cells (420±85 µm) to eight cells (861±237 µm), in line with the mitosis events. Both the average total edge measured (450±162 µm for euploid embryos and 489±215 µm for aneuploid embryos, p &lt; 0.01) and the average total of the difference between consecutive frames (135±47 µm for euploid embryos and 153±64 µm for aneuploid embryos, p &lt; 0.01) were higher for aneuploid embryos than for euploid embryos. A regression model to differentiate between the two classes achieved 73% sensitivity and 73% specificity on this dataset.

Limitations, reasons for caution

The main limitation of this study is the difficulty to correlate our findings to other measure of cell activity. A more robust AI function (using not only cell edges lengths) would be required for future analysis to measure the cell activity in cell division up to the blastocyst stage.

Wider implications of the findings

Our results show for the first time that an AI based system can precisely measure microscopic cell edges in the dividing embryo. Using this novel method, we could distinguish between euploid and aneuploid embryos. This non-invasive method could further enhance our knowledge of the developing embryo.

Trial registration number

Not Applicable

P–197 Two different strategies for embryo culture and selection: time-lapse with single-step medium and conventional incubator with sequential media. Are there differences in clinical results?

Study question

Is there a significant difference in the clinical results of embryos cultured in time-lapse systems with single-step medium and conventional benchtop incubators with sequential media?

Summary answer

Embryos cultured in time-lapse systems and single-step media are more likely to achieve an ongoing pregnancy and have higher implantation rates than those cultured otherwise.

What is known already

One of the strategies for embryo culture in IVF consisted in conventional benchtop incubators combined with sequential culture media (CI-Seq). New generation time-lapse systems provide useful information on the morphokinetics of embryo development, but also a stable culture environment where embryos can develop undisturbed until blastocyst stage when paired with single-step culture media (TLS-SS). These features have the potential to improve embryo development and selection. Nonetheless, there is inconclusive evidence of whether this new culture strategy has a significant effect on clinical results of ICSI treatments. Studies on the matter are heterogeneous and reduced in both number and sample size.

Study design, size, duration

Unicentric retrospective cohort study. We compared the results of 11471 blastocyst transferences from 10276 ICSI treatments performed during 4 consecutive years, where embryos were cultured either on CI with sequential media (N = 5255) or a TLS with single-step medium (N = 5021). 3922 of the totals were fresh embryo transfers (ET) and 7549 frozen-thawed ET. We compared the implantation rate (IR) and ongoing pregnancy rate (OGPR) in both study groups, stratifying by ovum origin.

Participants/materials, setting, methods

Three models of TLS were used for embryo culture: EmbryoScope, EmbryoScope Plus (Vitrolife) and GERI (Genea Biomedx), as well as one CI (ASTEC). Sequential media: Cook, Origio, Vitrolife; Single-step media: Gems, Irvine, Life Global. Embryo scoring and selection was performed by ASEBIR criteria in the CI group, and by morphological and morphokinetic assessment for embryos cultured in TLS. Embryos were extracted from the CI only for media change. Statistical analysis: ANOVA tests and Logistic regressions.

Main results and the role of chance

A general Logistic Regression was performed, including egg origin, PGT-A and culture strategy to explain their impact in OGPR. Egg origin (OR = 1,094 (95%CI: 1,015–1,179); P = 0,019) and culture strategy (OR = 1,141 (95%CI: 1,060–1,229); P &lt; 0,001) were statistically significant, which confirms the need for stratification due to the heterogeneity of the groups. The total IR in the TLS-SS group was 54,68±48,84%, significantly higher than that of CI-Seq (49,18±47,91%; P &lt; 0,001). In ovum-donation treatments, a complete Logistic Regression for OGPR, with all typical confounding variables (age, BMI, nº oocytes, fresh/frozen transfer, number and day of ET) resulted in an OR = 1,187 (95%CI: 1,074–1,313; P = 0,001) favoring culture in TL-SS. IR in these treatments were 61,98±47,68% in TL-SS vs 55,08±46,58% in CI-Seq (P &lt; 0,001) in fresh transfers and 51,48±48,91% in TL-SS vs 44,39±47,67% in CI-Seq (P &lt; 0,001) in frozen-thawed ET. In autologous treatments with PGT a similar regression yielded an OR = 1,055 (95%CI: 0,889–1,252; P = 0,542) for culture strategy. The IR of genetically tested ET was not significantly different: 53,08±49,49% for TL-SS, 50,90±49,07% for CI-Seq, P = 0,246. In autologous procedures without PGT, culture strategy was not significant for OGPR (OR = 0,998 (95%CI: 0,835–1,191), P = 0,979) nor IR of fresh (49,75±48,91% TL-SS vs 44,23±47,36% CI-Seq; P = 0,081) nor frozen-thawed transferences (50,77±48,33% TL-SS vs 50,67±47,33% CI-Seq; P = 0,970).

Limitations, reasons for caution

After fertilization check, embryos were evaluated exclusively on D5/6. On D3, embryos cultured in CI were taken out only for a quick media change, but not for evaluation, and all handling was done in isolette cabins with controlled environmental conditions. Being a retrospective study, there is high variability in population.

Wider implications of the findings: A more homogenous prospective study, including comparison in life-birth rates, is necessary to extract final conclusions. However, our results suggest that the introduction of TLS and SS media in IVF laboratories might be a valid strategy to increase clinical results, especially in fresh embryo, thanks to an improved embryo selection.

Trial registration number

Not applicable

P–144 Undisturbed culture in time-lapse systems improves embryo development and quality

Study question

Does culture in integrated time-lapse systems (TLS) improve embryo development and blastocyst quality compared to conventional benchtop incubators (CI), within the same IVF laboratory?

Summary answer

Under similar conditions, culture in TLS resulted in a significant increase in blastocyst rate, top quality blastocyst rate and proportion of biopsied embryos per treatment

What is known already

Integrated TLS have the potential of delivering a stable and undisturbed environment throughout the whole embryo culture, avoiding taking them out for assessment. However, there is still lack of quality evidence of the performance of these incubators compared to CI at supporting embryo culture until blastocyst stage. Studies abording this issue are still scarce, heterogeneous and have a small sample size. Although some authors have reported an improvement in embryo development and quality using TLS, global results are inconsistent. To our knowledge, the present study evaluates the effect of TLS on embryo quality on the largest sample size yet.

Study design, size, duration

Unicentric retrospective cohort study including 14248 ICSI treatments from 2016 to October 2020, with both autologous and donated oocytes. We compared blastocyst rate (BR) and proportion of top-quality blastocysts (TQB=Morphology ASEBIR score A) per treatment between those using TLS (N = 7500) and CI (N = 6748), and the proportion of embryos biopsied (EB) in cycles with pre-implantation genetic testing (PGT-A; N = 2642). We performed a sub-analysis in treatments using single-step culture medium (N-TLS=4398, N-CI=1140) in both types of incubators.

Participants/materials, setting, methods

Embryo cohorts were cultured until blastocyst stage in one of 3 TLS: EmbryoScope, EmbryoScope Plus (Vitrolife,) and Geri (Genea Biomedx), or in a CI (ASTEC). Embryo quality was assessed following ASEBIR morphological criteria. Culture protocols and media changed during the included time period. For that reason, we did a sub-study in the treatments performed since the implementation of Gems® (Genea Biomedx) single-step (SS) culture medium in all incubators. Statistical analysis was done using ANOVA tests.

Main results and the role of chance

Treatments were differently distributed and heterogeneous in terms of number of oocytes obtained per patient, so we stratified the analysis according to ovum origin and compared mean rates per cycle instead of total number of embryos per group. BR was statistically higher (P &lt; 0,001) in the TLS group, in both autologous (62,98±29,37% vs 59,49±31,09% in CI) and oocyte donation treatments (69,25±22,07% vs 66,27±23,28% in CI). Proportion of TQB was also significantly higher in the TLS in both types of cycles (P &lt; 0,001): 3,60±12,29% in TLS vs 2,27±9,71% in CI in autologous cycles, 8,68±15,31% in TLS vs 7,32±14,02% CI in ovum donation cycles. Results were corroborated in the SS media sub-study (P &lt; 0,05): BR was 63,87±29,23% in TLS vs 57,53±30,61% in CI with autologous oocytes, and 70,76±21,63% in TLS vs 67,39±22,68% in CI with donated oocytes; TQB rates were 3,66±12,06% in TLS vs 2,05±9,26% in CI in autologous treatments and 8,81±15,21% in TLS vs 6,84±12,91% in CI in ovum donation treatments. Regarding PGT-A treatments, we found no significant difference in the biopsy rate in the total comparison, although the rate significantly increased in the TLS group since the implementation of single-step medium (52,36±24,69% in TLS vs 48,63±22,56% in CI; P = 0,007)

Limitations, reasons for caution

Not only culture conditions varied over time, but also the number of TLS in the laboratory, which increased lately. Hence, even though the most recent treatments included in the all-SS sub-study are more homogeneous in terms of culture conditions, they are unbalanced regarding the distribution among incubators.

Wider implications of the findings: Our results demonstrate the superiority of TLS coupled with single-step culture media against traditional embryo culture systems at supporting embryo development. The optimal environment provided by TLS enhances embryo development until blastocyst stage as well as their quality, increasing the cumulative chances of getting a life-birth for each patien.

Trial registration number

Not applicable

O-121 Exploring non-invasive methods to predict Ploidy Status: Combination of blastocyst morphology image analysis and proteomic profiles by using Artificial Neural Networks

Study question

Is the blastocyst morphology image analysis combined with the protein content of spent embryo culture medium a suitable way to predict embryo ploidy?

Summary answer

Morphological variables from blastocyst image analysis combined with IL-6 or MMP-1 concentration in spent culture medium showed more than 80% of accuracy for euploidy prediction.

What is known already

An artificial intelligence model based on the proteomic profile of euploid embryos and morphological data from blastocyst time-lapse images has been recently published (Bori et al., 2020). The most promising artificial neural network (ANN) algorithm considered 20 morphological variables extracted from image analysis and two proteins detected in embryo culture medium (MMP-1 and IL-6). The overall success rate on blind test data was 72.7% for live birth prediction. The main aim of the present study was to check if the same morphological variables combined with MMP-1 or IL-6 with a cost-effective technique could discriminate between euploid and aneuploid embryos.

Study design, size, duration

This prospective study included 120 embryos from the preimplantation genetic testing for aneuploidies (PGT-A) program. A single blastocyst image was obtained for each embryo and their spent culture medium was collected on the day 5/6 of embryo development (day of trophectoderm biopsy). Morphological variables were extracted for all the blastocyst. On the other hand, we quantified IL-6 levels of 67 embryos and MMP-1 levels of 53 embryos. Resulting parameters were used to predict PGT-A results.

Participants/materials, setting, methods

Blastocyst images were imported into Matlab software and segmented into regions of interest. We obtained 20 mathematical variables related to measurements of areas, number of pixels and texture analysis. Chromosome analysis was performed using next-generation sequence technology. In parallel, 20 µL of spent culture medium from each blastocyst was analyzed with ELISA kits (IL-6 or MMP-1). Protein concentrations and morphological variables were used as input data for an ANN associated with genetic algorithms.

Main results and the role of chance

The euploid rate for the set of embryos included in the IL-6 group was 51.4%. The ANN was trained with 49 embryos and blind tested with 18 embryos. Following results correspond to euploidy prediction on the blind test. The sensitivity, specificity, accuracy and area under the ROC curve (AUC) were: 0.56, 0.78, 0.67 and 0.72 considering only IL-6 values; 0.88, 0.78, 0.83 and 0.61 considering IL-6 values and blastocyst morphological data extracted from the image analysis. The euploid rate for the set of embryos included in the MMP-1 group was 51.9%. The ANN was trained with 39 embryos and blind tested with 14 embryos. Following results correspond to euploidy prediction on the blind test. The sensitivity, specificity, accuracy and AUC were: 0.71, 0.57, 0.64 and 0.67 considering only MMP-1 values; 0.86, 0.86, 0.86 and 0.61 considering MMP-1 values and morphological data extracted from the image analysis.

Limitations, reasons for caution

The detection limit in protein quantification is the main limitation of our study. The small number of embryos and the specific culture medium used should be considered for the model application.

Wider implications of the findings

Our preliminary results showed that blastocyst morphology and embryo secretomics could be useful for euploidy prediction by using artificial intelligence techniques. These findings may contribute to the emerging era of non-invasive preimplantation genetic testing (ni-PGT-A).

Trial registration number

not applicable

P–141 Artificial intelligence system for the automation of the blastocyst morphology evaluation in GERI Time-lapse Incubator

Study question

Can an Artificial Intelligence (AI) system (hand-crafted vs. deep learning techniques) based on single embryo image analysis from a GERI time-lapse incubator (TL) evaluate the blastocyst morphology?

Summary answer

Our hand-crafted method trained with blastocyst images from Geri-TL evaluated and classified parameters regarding to embryo quality with a global precision of 63.7% in blind-test.

What is known already

Recent studies have shown that AI can improve automatic grading and embryo selection. The approaches that have been carried out are very different, but all they conclude that there is a great potential (Rad2019, Manoj2020, Thirumalaraju2020). As we know, conventional embryo evaluation is performed manually based on the morphology of the blastocyst, therefore, it should be possible to replicate this process. In this study, we implemented different methods to analyse the behaviour and performance of an AI doing embryology tasks.

Study design, size, duration

Our study consisted of a retrospective analysis for the automatization of embryo evaluation with different approaches. We developed our models based on 715 images extracted from GERI TL Videos (Genea, Australia) from a single IVF center. Database was divided into 3 classes depending on the quality of the embryo according to ASEBIR morphology criteria (high; medium and low-quality). All the images were divided into 70% for training, 15% for validating and 15% for testing.

Participants/materials, setting, methods

We developed an automated AI algorithm to extract and classify features from images at 111,5 hpi of embryos cultured in GERI TL. Hand-crafted features from texture information are extracted to feed the classification algorithm. A statistical analysis is carried out to select the more discriminative variables. Parallelly, a deep neural network was built to compare performance of automatic and hand-crafted features. Additionally, we trained a model to detect embryo in the well.

Main results and the role of chance

High-quality, medium-quality and low-quality sensitivity were 73%, 56% and 72% for hand-crafted method and 76%, 53% and 22% for deep learning approach, respectively. High-quality, medium-quality and low-quality precision were 66%, 56% and 76% for hand-crafted method and 40%, 60% and 55% for deep learning approach, respectively. The global accuracy associated with each method was 64% and 50%. Also, we noticed that results were higher when we applied our embryo masks that avoid irrelevant information. In this initial attempt, our results showed that it is possible to replicate the embryo evaluation process.

Limitations, reasons for caution

The low results obtained in our deep learning model due to the absence of an extent dataset did not allow to obtain a model applicable to the clinic. However, the preliminary study let us to conclude the high potential of the approach.

Wider implications of the findings: Our results showed a potential automatization of the embryo evaluation process in Geri TL where the available software for embryo selection does not provide such option. Our findings leaded to an increase in objectification, a reduction of the workload of the embryologist and the research of new unknown morphological variables.

Trial registration number

Not applicable

P-203 Applying artificial intelligence for ploidy prediction: The concentration of IL-6 in spent culture medium, blastocyst morphological grade and embryo morphokinetics as variables under consideration

Study question

Would it be possible to predict embryo ploidy by taking into account conventional morphological and morphokinetic parameters together with IL-6 concentration in spent culture medium?

Summary answer

Our artificial neural network (ANN) trained with blastocyst morphology, embryo morphokinetics and IL-6 concentration distinguished between euploid/aneuploid embryos in 65% of the testing dataset.

What is known already

The analysis of spent embryo culture media represents the protein and metabolic state of the embryo and could be a non-invasive method of obtaining information about embryo quality. The impact of the presence/absence of several proteins in embryo culture samples over clinical results has been widely studied. The IL-6 is one of the most mentioned protein for its effect on embryo development, implantation and likelihood of achieving a live birth. In this initial attempt, we examined the predictive value for euploidy of a model that took into account the concentration of IL-6 in the spent culture medium.

Study design, size, duration

This prospective study included 319 embryos with PGT-A results. Out of the total, 127 were euploid and 192 aneuploid embryos. Concentration of IL-6 in spent embryo culture media (collected on the day of trophectoderm biopsy-fifth/sixth day of development), morphokinetic parameters (division time to 2 cells-t2; to 3 cells-t3, to 4 cells-t4; to 5 cells-t5 and time of blastocyst formation-tB) and blastocyst morphological grade (according to ASEBIR criteria) were considered to predict the embryo ploidy.

Participants/materials, setting, methods

Embryos were cultured in EmbryoScope. The chromosome analysis was performed using next-generation sequence technology. The concentration of IL-6 was measured in 20µL of spent embryo culture media with ELISA kits. Morphokinetic parameters were automatically annotated and the blastocyst morphology was evaluated by senior embryologists based on blastocele expansion, inner cell mass and trophectoderm quality. All the embryos were divided into 70% for training, 15% for validating and 15% for testing our ANN model with MatLab®.

Main results and the role of chance

The general description for the euploid embryo population was the following: 2% of the embryos were graded as A, 71% were graded as B and 28% were graded as C; the means and standard deviations were 25.32±2.97 hours (h) for t2, 35.33±5.15h for t3, 37.30±5.43h for t4, 48.24±6.62h for t5 and 103.93±12.8h for tB; and the average of IL-6 concentration was 1.51±0.70 pg/ml. The general description for the aneuploid embryo population was the following: 1% of the embryos were graded as A, 48% were graded as B and 51% were graded as C; the means and standard deviations were 26.13±3.51h for t2, 36.70±4.29h for t3, 38.20±4.24h for t4, 49.86±6.89h for t5 and 107.10±8.29h for tB; and the average of IL-6 concentration was 1.47±0.71 pg/ml. Our ANN model showed a higher general success rate as we increased the variables considered in the final prediction of euploid embryos. The accuracy, sensitivity and specificity for the testing dataset were: 0.60, 0.12 and 0.87 with morphokinetic parameters; 0.63, 0.24 and 0.93 with morphokinetics and IL-6 concentration; and 0.65, 0.16 and 0.96 with morphokinetics, IL-6 concentration and blastocyst morphological grade.

Limitations, reasons for caution

The low sensitivity and high specificity achieved in our models indicated that they were more capable of detecting aneuploid than euploid embryos. As this was a preliminary study, the small number of embryos included in the test (n = 48) was also a limitation.

Wider implications of the findings

The results showed that our model tended to classify the embryos as aneuploid. More euploid embryos would be necessary to train our model and achieve better results in the prediction of chromosomally normal embryos. Further studies with large number of embryos and additional variables could improve the non-invasive ploidy prediction.

Trial registration number

not applicable

P–135 Artificial neural networks (ANNs) for live birth prediction in frozen embryo transfers: the strength of post-warmed blastocyst dynamics

Study question

Does the post-warmed blastocyst dynamics have an impact over the likelihood of achieving a live birth?

Summary answer

Variables related to dynamics of vitrified/warmed blastocysts have shown a greater effect on the live birth prediction than only embryo morphological quality through artificial intelligence.

What is known already

Morphological dynamics of vitrified/warmed blastocysts were described by Coello et al., in 2017. The investigated markers were the thickness of zona pellucida (µm) and blastocysts area (µm2) after warming and before transfer, the area of the inner cell mass (µm2), time of initiation of reexpansion (in minutes), and presence of collapse or contraction. They found a correlation between blastocyst reexpansion and implantation rate and developed a hierarchical model for implantation prediction. In our study, we evaluated the post-warmed blastocyst dynamics for live birth prediction by using novel artificial intelligence techniques.

Study design, size, duration

This retrospective analysis included 415 vitrified/warmed blastocysts with known live birth data. Blastocysts after warming were placed in EmbryoScope (Vitrolife) immediately until embryo transfer. Embryo evaluation and selection were performed by senior embryologists according to fresh blastocyst morphology (before vitrification). Then, parameters related to post-warmed blastocyst dynamics were calculated. Finally, these variables and the embryo morphological grade before the vitrification were used as input data for ANNs optimized with genetic algorithm for live birth prediction.

Participants/materials, setting, methods

Blastocysts were vitrified and warmed by the Cryotop method (Kitazato,Biopharma). During the period between the warming procedure and the embryo transfer, the following variables were measured with the drawing tools provided by the EmbryoViewer workstation: zona pellucida thinning (µm), blastocyst expansion (um) and the speed of these two events (µm/h). Finally, multilayer perceptron neural networks were trained with data of 331 embryos by using the backpropagation learning algorithm and tested with data of 84 embryos.

Main results and the role of chance

We trained and tested three architectures of ANNs with different input variables as follows: post-warmed variables (thinning of the zona pellucida, blastocyst expansion, thinning speed and expansion speed) and morphological grade (A, B or C) for ANN1, only post-warmed variables for ANN2 and only morphological grade for ANN3. The highest success rate when ANNs classified embryos as positive and negative live birth (LB+ and LB-) was achieved by combining post-warmed variables and morphological grade before embryo vitrification. The general accuracies for the blind tests were: 73.8% for ANN1, 66.7% for ANN2 and 71.4% for ANN3. Likewise, this combination achieved the highest AUC on test dataset to predict LB- (0.76 for ANN1, 0.74 for ANN2 and 0.67 for ANN3). However, the ANN2 trained with only post-warmed variables showed the best capacity to predict LB+ with an AUC of 0.73 (versus 0.46 for ANN1 and 0.5 for ANN3).

Limitations, reasons for caution

The main limitation is the subjectivity of manual annotations, although only one embryologist participated in this task.

Wider implications of the findings: The dynamics of vitrified/warmed blastocysts prior to embryo transfer could be more relevant variables than the morphological quality on day 5 before the cryopreservation. The analysis of embryo behavior after warming could improve clinical outcomes in frozen embryo transfers.

Trial registration number

none

O-085 In-depth analysis of embryo development: Differences among monosomic, trisomic and chromosomally chaotic embryos compared to euploid embryos

Study question

Is there any visible variation in the development of aneuploid embryos depending on the type of chromosome abnormality?

Summary answer

There were significant visible differences in the development of euploid, monosomic, trisomic and, especially, chaotic embryos.

What is known already

Aneuploidy rates are remarkably high in in vitro fertilized human embryos, with up to 50% of embryos diagnosed as aneuploid based on preimplantation genetic testing for aneuploidies (PGT-A). However, very little is known about the impact of specific aneuploidies during the early human embryo development. A recent publication showed that embryos with single chromosomal gain or loss reached the blastocyst stage later or earlier depending on the chromosome affected (Shahbazi et al., 2020). In our study, we wanted to detect observable differences in embryo behavior between embryos with different chromosomal abnormalities during the entire in vitro development.

Study design, size, duration

This was a retrospective study including 2,500 blastocysts with PGT-A results. Embryos were cultured in EmbryoScope systems until the fifth/sixth day of development (up to the time of trophectoderm biopsy). Automatic-annotations for division times and quality gradings were supervised routinely by senior embryologists using Guided Annotations Tool. Out of the total, 1,000 were euploid embryos used for reference and 1,500 were aneuploid embryos with one or more defects, including monosomic, trisomic and chromosomally chaotic embryos.

Participants/materials, setting, methods

Chromosome analysis was performed using next-generation sequence technology. Then, an in-depth analysis of time-lapse videos and supervised-automatic annotations was performed. We calculated the proportion of embryos, in each aneuploid category, that reached one specific event later than the expected value for euploid embryos plus one standard deviation. Later, we calculated the “relative risk” of an embryo of reaching the milestone late. We did the same for the time between milestones and for pairs of milestones.

Main results and the role of chance

Every aneuploid category was more likely to reach each specific embryo developmental event later than euploid embryos and the time gaps between developmental milestones were also statistically longer in aneuploid embryos (p &lt; 0.0001). The following results were the most interesting relative risks (RR) when we compared the proportion of embryos (in each aneuploid category) to the proportion of euploid embryos (RR for euploid = 1). For reaching the division time to two cells (t2): 1.31 in monosomic embryos, 1.50 in trisomic embryos and 2.43 in chaotic embryos. For the division time to four cells (t4): 1.42 in monosomic embryos, 1.54 in trisomic embryos and 3.07 in chaotic embryos. For the division time to eight cells (t8) and the time of starting blastulation: 1.45 in monosomic embryos, 1.22 in trisomic embryos and 2.74 in chaotic embryos. Combined milestones were stronger indicators than each milestone by itself, the RR were: 1.63 in monosomic embryos, 1.81 in trisomic embryos and 3.35 in chaotic embryos for t2 and t4; 1.50 in monosomic embryos, 1.80 in trisomic embryos and 2.84 in chaotic embryos for t2 and t8; 1.46 in monosomic embryos, 1.90 in trisomic embryos and 3.43 in chaotic embryos for t4 and t8.

Limitations, reasons for caution

At this stage, we did not go down to specific chromosome abnormality as there were very few cases in each fully detailed category. Also, not all the embryos reached every developmental milestone.

Wider implications of the findings

Aneuploid embryos were significantly different from euploid embryos in the first five days of development. A large proportion of aneuploid embryos could be rejected because their developmental milestones falling outside the normal range. This could form part of an automated system for determining euploidy/aneuploidy from observation of embryos in vitro.

Trial registration number

1902-VLC-018-MM

A new system of sperm cryopreservation: evaluation of survival, motility, DNA oxidation, and mitochondrial activity

BACKGROUND

Sperm vitrification (V) is a method for cryopreservation, without the use of conventional cryoprotectants, by plunging the sperm suspension directly into liquid nitrogen (LN25).

OBJECTIVE

This study aimed to compare the new system of V with conventional freezing (CF) protocol using fresh spermatozoa as reference (C).

MATERIAL AND METHODS

Prospective cohort study. A total of 47 sperm samples from men attending the infertility clinic at Instituto Valenciano de Infertilidad Valencia. The sperm V solution was 0.3 M trehalose-sucrose and plunged directly in liquid nitrogen in microdroplets of 5-10 lL, using a new system collector of V. Sperm viability indicators such as sperm motility, vitality rates, mitochondrial function, and sperm DNA oxidation were assessed before and after cryopreservation. Sperm motility and vitality analysis were performed according to published guidelines of the World Health Organization (WHO, 2010). Mitochondrial function was evaluated using JC-1 (fluorescent cationic dye, 5,50,6,60-tetrachloro-1-10,3,30-tetraethyl-benzamidazolocarbocyanin iodide). Sperm DNA oxidation was determined using a fluorescent assay (Oxy-DNA test) for the detection of 8-oxoguanine. The evaluation was carried out before and after cryopreservation using flow cytometry. Statistical analysis was performed using ANOVA and chi-square test, and p < 0.05 was considered statistically significant.

RESULT(S)

Sperm parameters, including progressive motility, total motility, and viability, observed after cryopreservation were as follows: C = 74.9% [1] 12.3, CF = 27.2% [1] 8.4, V = 42.3% [1] 9.3, p < 0.001; C = 90.1 [1] 6.8, CF = 42.0 [1] 12.9, V = 61.4 [1] 11.8, p < 0.001; C = 90.0% [1] 7.4, CF = 42.5% [1] 14.6, V = 70.9% [1] 6.5, p < 0.001, respectively. Regarding Oxy-DNA and mitochondrial activity, they were significantly affected in both groups (V and CF) when compared to the control group.

DISCUSSION

The sperm V and CF have negative impact on sperm parameters as well as DNA integrity and mitochondrial activity. However, sperm V presented improved sperm motility recovery, similar levels of DNA oxidation, and, moreover, a slightly increase in mitochondrial activity when compared to the conventional method.

CONCLUSION(S)

V as an optimal protocol for sperm cryopreservation.

Origin and composition of cell-free DNA in spent medium from human embryo culture during preimplantation development

STUDY QUESTION

What is the origin and composition of cell-free DNA in human embryo spent culture media?

SUMMARY ANSWER

Cell-free DNA from human embryo spent culture media represents a mix of maternal and embryonic DNA, and the mixture can be more complex for mosaic embryos.

WHAT IS KNOWN ALREADY

In 2016, ~300 000 human embryos were chromosomally and/or genetically analyzed using preimplantation genetic testing for aneuploidies (PGT-A) or monogenic disorders (PGT-M) before transfer into the uterus. While progress in genetic techniques has enabled analysis of the full karyotype in a single cell with high sensitivity and specificity, these approaches still require an embryo biopsy. Thus, non-invasive techniques are sought as an alternative.

STUDY DESIGN, SIZE, DURATION

This study was based on a total of 113 human embryos undergoing trophectoderm biopsy as part of PGT-A analysis. For each embryo, the spent culture media used between Day 3 and Day 5 of development were collected for cell-free DNA analysis. In addition to the 113 spent culture media samples, 28 media drops without embryo contact were cultured in parallel under the same conditions to use as controls. In total, 141 media samples were collected and divided into two groups: one for direct DNA quantification (53 spent culture media and 17 controls), the other for whole-genome amplification (60 spent culture media and 11 controls) and subsequent quantification. Some samples with amplified DNA (N = 56) were used for aneuploidy testing by next-generation sequencing; of those, 35 samples underwent single-nucleotide polymorphism (SNP) sequencing to detect maternal contamination. Finally, from the 35 spent culture media analyzed by SNP sequencing, 12 whole blastocysts were analyzed by fluorescence in situ hybridization (FISH) to determine the level of mosaicism in each embryo, as a possible origin for discordance between sample types.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Trophectoderm biopsies and culture media samples (20 μl) underwent whole-genome amplification, then libraries were generated and sequenced for an aneuploidy study. For SNP sequencing, triads including trophectoderm DNA, cell-free DNA, and follicular fluid DNA were analyzed. In total, 124 SNPs were included with 90 SNPs distributed among all autosomes and 34 SNPs located on chromosome Y. Finally, 12 whole blastocysts were fixed and individual cells were analyzed by FISH using telomeric/centromeric probes for the affected chromosomes.

MAIN RESULTS AND THE ROLE OF CHANCE

We found a higher quantity of cell-free DNA in spent culture media co-cultured with embryos versus control media samples (P ≤ 0.001). The presence of cell-free DNA in the spent culture media enabled a chromosomal diagnosis, although results differed from those of trophectoderm biopsy analysis in most cases (67%). Discordant results were mainly attributable to a high percentage of maternal DNA in the spent culture media, with a median percentage of embryonic DNA estimated at 8%. Finally, from the discordant cases, 91.7% of whole blastocysts analyzed by FISH were mosaic and 75% of the analyzed chromosomes were concordant with the trophectoderm DNA diagnosis instead of the cell-free DNA result.

LIMITATIONS, REASONS FOR CAUTION

This study was limited by the sample size and the number of cells analyzed by FISH.

WIDER IMPLICATIONS OF THE FINDINGS

This is the first study to combine chromosomal analysis of cell-free DNA, SNP sequencing to identify maternal contamination, and whole-blastocyst analysis for detecting mosaicism. Our results provide a better understanding of the origin of cell-free DNA in spent culture media, offering an important step toward developing future non-invasive karyotyping that must rely on the specific identification of DNA released from human embryos.

STUDY FUNDING/ COMPETING INTEREST

This work was funded by Igenomix S.L. There are no competing interests.

High sperm DNA fragmentation delays human embryo kinetics when oocytes from young and healthy donors are microinjected

BACKGROUND

Time-lapse monitoring (TLM) technology has been implemented in the clinical setting for the culture and selection of human embryos. Many studies have assessed the association between sperm DNA fragmentation (sDNAf) and clinical outcomes after ART, but little is known about the influence of sDNA on embryo morphokinetics.

OBJECTIVES

The objective of this retrospective study, which includes 971 embryos from 135 consecutive ICSI cycles (56 cases with own oocytes, 79 with oocytes from young and healthy donors), was to assess if sDNAf has an impact on embryo morphokinetics.

MATERIALS AND METHODS

Samples used to perform ICSI were analyzed by the flow cytometry TUNEL assay, and embryo development was assessed through an EmbyoScope^® system. The association between sDNAf and the timings of cell cleavage was analyzed by categorizing the first variable into quartiles: ≤6.50%; 6.51-10.70%; 10.71-20.15%; >20.15%.

RESULTS

In cases where sDNAf was above 20.15% (the upper quartile), embryos derived from donated oocytes (n = 644) showed significantly slower divisions. Such association was not observed in embryos obtained from the patients' own oocytes (n = 327). The embryo cleavage pattern (either normal, direct from 1 to 3 blastomeres, direct from 1 to 4 blastomeres, incomplete, reversed or asynchronous) was independent of the sDNAf level. Blastocyst arrival rate was 63.0% and the rate of good quality embryos (transferred and frozen embryos divided by the number of zygotes) was 45.49%. Neither parameter was related to the levels of sDNAf.

DISCUSSION

According to our results, the association between high sDNAf and donated oocytes led to delayed cell division. To our knowledge, this is the first study suggesting that sDNAf can delay human embryo cleavage timings when oocytes from donors are inseminated.

CONCLUSIONS

This finding may indicate that, in the presence of increased DNA damage, time is needed before the first embryonic cell division for the activation of the optimal DNA repairing machinery in higher quality oocytes.