Discard, or not discard, that is the question. An international survey among 117 embryologists about their decision on 50 poor-quality/day7 blastocysts cultured in time-lapse incubators.

Abstract Study question Are decisions on day7 and/or poor-quality blastocysts’ (PQB; <Gardner’s BB) use consistent among embryologists of diverse European countries and what factors influence them? Summary answer “Discard” choice prevalence was ≈40%, however inter-rater agreement was just fair (Fleiss-k=0.26). Country of practice, maternal age and number of sibling embryos influence each decision. What is known already Blastocyst morphokinetics and morphological quality are associated with competence and used to make clinical decisions, even though evaluations are poorly reproducible across embryologists. Moreover, the increasing utilization of PQB and adoption of culture beyond 144 hours-post-insemination is further challenging the decision-making process. Previous surveys reported limited concordance among embryologists in the “discard”/“use” choices made for day7 and/or PQB based on single 2D-pictures without cycle/patient information. However, for instance whole embryo preimplantation development, reproductive history, number of sibling embryos, can influence each decision. Different regulations and mindsets across countries may further influence these choices and require investigation. Study design, size, duration Anonymous survey in Microsoft-Forms run within a large IVF-network. Each laboratory-director shared a link to the survey with his/her colleagues via 3 e-mails sent weekly between 22/12/2023 and 12/1/2023. 117 embryologists participated representing 6 European Countries, 9 IVF-groups, and 28 centers. Raters inspected EmbryoScope videos of 50 PQBs and/or day7 blastocysts’ whole preimplantation development and decided whether to “use” (“transfer-fresh”/“cryopreserve”/“biopsy and cryopreserve”) or “discard” each of them. Inter-rater agreement was measured with Fleiss-k. Participants/materials, setting, methods Couples’ information (age, infertility diagnosis, previous attempts, sperm analysis, number of sibling blastocysts obtained) were provided, and participants were asked their years of experience, center location, average number of cycles and average maternal age, number of colleagues, presence of time-lapse-incubators. The AI-score (CHLOE-EQ, Fairtility and iDAScore v1.0, Vitrolife), chromosomal diagnosis and clinical outcomes were known for all embryos by one embryologist not involved in the survey, but the participants were blinded to them. Main results and the role of chance Participants were Italian (40%,N=47), Spanish (24%,N=28), Portuguese (5%,N=6), Czech (5%,N=6), Swedish (23%,N=27) and Icelandic (3%,N=3). 2263(38.7%) “discard” and 3587(61.3%) “use” decisions were recorded. Czech, Portuguese, and Italian embryologists expressed lower (17±7%,23±14% and 27±18%), Spanish intermediate (37±16%), and Nordic higher (67±11%) “discard” decision rates.The prevalence of “discard” responses per embryo was 37.4±24.2%(2-87). The larger the number of sibling blastocysts the higher the embryologists’ propensity to “discard” PQBs/day7 (unstandardized coefficient-B:+4.4%,95%CI:+0.9 to + 7.9,p=0.015). The most prevalent “use” choice was “biopsy and cryopreserve” (33.1±21.7%,2-78). Maternal age (unstandardized coefficient-B:+2.2%,95%CI:+1.3 to + 3.8,p<0.01) and number of sibling blastocysts (unstandardized coefficient-B:-9.2%,95%CI:-15.2% to -3.3%,p<0.01) influenced this rate.Overall, inter-rater agreement was 0.26 (standard-error:0.003;“fair”), with “moderate” agreement for Czech and Portuguese (0.41,standard-error:0.037), “fair” for Spanish (0.38,standard-error:0.007), Italian and Nordic embryologists (0.28,standard-error:0.006 and 0.009).CHLOE-EQ and iDAScore v1.0 were not associated with embryologists’ decisions. No difference was shown for AI-scores in euploid versus aneuploid blastocysts (CHLOE-EQ: 0.2±0.32,0-0.9 versus 0.2±0.29,0-0.93; iDAScore v1.0: 4.2±1.6,2.2-6.7 versus 4.3±1.5,2.1-9), while the embryologists more often chose “discard” among the latter group (28.3±21%,9-71 versus 41.6±24.8%,2-87). Five blastocysts were transferred and 3 implanted (CHLOE-EQ: 0.001,0.416 and 0.003; iDAScore v1.0: 2.6,5.0 and 6.6; “discard” choice rates: 19%,15% and 10%). Limitations, reasons for caution All embryologists were asked to decide regardless of the regulation enforced in their countries (e.g., PGT-A forbidden, discarding viable embryos not allowed). Nonetheless, the legislative, social, and clinical background might still have affected their choice. The survey included only private IVF clinics located in Europe. Wider implications of the findings European embryologists’ decision-making regarding PQB/day-7 embryos is inconsistent. Mostly, legislative/clinical background and cycles’ characteristics influence each decision. However, this practice has clinical implications, especially in poor-prognosis patients. Artificial-Intelligence may improve the reproducibility by removing intrinsic human subjectivity. However, it is still currently underpowered to assess these outlier embryos Trial registration number Not applicable