DESIGN: De-identified images were provided retrospectively or collected prospectively by IVF clinics using the artificial intelligence model in clinical practice. A total of 9359 images were provided by 18 IVF clinics across six countries, from 4709 women who underwent IVF between 2011 and 2021. Main outcome measures included clinical pregnancy outcome (fetal heartbeat at first ultrasound scan), embryo morphology score, and/or pre-implantation genetic testing for aneuploidy (PGT-A) results.
RESULTS: A positive linear correlation of artificial intelligence scores with pregnancy outcomes was found, and up to a 12.2% reduction in time to pregnancy (TTP) was observed when comparing the artificial intelligence model with standard morphological grading methods using a novel simulated cohort ranking method. Artificial intelligence scores were significantly correlated with known morphological features of embryo quality based on the Gardner score, and with previously unknown morphological features associated with embryo ploidy status, including chromosomal abnormalities indicative of severity when considering embryos for transfer during IVF.
CONCLUSION: Improved methods for evaluating artificial intelligence for embryo selection were developed, and advantages of the artificial intelligence model over current grading approaches were highlighted, strongly supporting the use of the artificial intelligence model in a clinical setting.
SUMMARY ANSWER: The inter-observer agreement among embryologists deciding whether to freeze blastocysts of marginal morphology was low and was not improved by a modified grading system.
WHAT IS KNOWN ALREADY: While previous research on inter-observer variability on the decision of which embryo to transfer from a cohort of blastocysts is good, the impact of grading variability regarding decision to freeze borderline blastocysts has not been investigated. Agreement for inner cell mass (ICM) and trophectoderm (TE) grade is only fair, factors which contribute to the grade that influences decision to freeze.
STUDY DESIGN, SIZE, DURATION: This was a prospective study involving 18 embryologists working at four different IVF clinics within a single organisation between January 2019 and July 2019.
PARTICIPANTS/MATERIALS, SETTING, METHODS: All embryologists currently practicing blastocyst grading at a multi-site organisation were invited to participate. The survey was comprised of blastocyst images in three planes and asked (i) the likelihood of freezing and (ii) whether the blastocyst would be frozen based on visual assessment. Blastocysts varied by quality and were categorised as either top (n = 20), borderline (n = 60) or non-viable/degenerate quality (n = 20). A total of 1800 freeze decisions were assessed. To assess the impact of grading criteria on inter-observer agreement for decision to freeze, the survey was taken once when the embryologists used the Gardner criteria and again 6 months after transitioning to a modified Gardner criterion with four grades for ICM and TE. The fourth grade was introduced with the aim to promote higher levels of agreement for the clinical usability decision when the blastocyst was of marginal quality.
MAIN RESULTS AND THE ROLE OF CHANCE: The inter-observer agreement for decision to freeze was near perfect (kappa 1.0) for top and non-viable/degenerate quality blastocysts, and this was not affected by the blastocysts grading criteria used (top quality; P = 0.330 and non-viable/degenerate quality; P = 0.18). In contrast, the cohort of borderline blastocysts received a mixed freeze rate (average 52.7%) during the first survey, indicative of blastocysts that showed uncertain viability and promoting significant disagreement for decision to freeze among the embryologists (kappa 0.304). After transitioning to a modified Gardner criteria with an additional grading tier, the average freeze rate increased (64.8%; P Blastocyst assessment was performed from time-lapse images in three planes, rather than with a microscope in the laboratory. The inter-observer agreement for decision to freeze may be lower for embryologists working in different clinics with different grading protocols.
WIDER IMPLICATIONS OF THE FINDINGS: The decision to freeze a blastocyst with borderline morphology is a common clinical issue that has the potential to arise for any patient during blastocyst culture. Disagreement for decision to freeze these blastocysts, and therefore clinical usability in frozen embryo transfer cycles, affects consistency in patient care due to a potential impact on cumulative live birth rates, as well as financial, emotional and time costs associated with the frozen embryo transfer cycles. We demonstrate significant disagreement for decision to freeze borderline blastocysts among embryologists using the same grading scheme within a large multisite organisation, a phenomenon which was not improved with a modified grading system. Decision-making around borderline embryos is an area requiring further research, especially as studies continue to demonstrate the reduced but modest live birth rates for low quality blastocysts (Grade C). These results provide support for emerging technology for embryo assessment, such as artificial intelligence.
STUDY FUNDING/COMPETING INTEREST(S): None declared.
TRIAL REGISTRATION NUMBER: Not applicable.
MATERIAL/METHODS: Fifty female mice, aged 4-6 weeks, were used in this study. Animals were superovulated, cohabitated overnight, and sacrificed. Fallopian tubes were excised and flushed. Embryos at the 2-cell stage were collected and cultured to obtain 4- and 8-cell stages before being cryopreserved using vitrification and slow freezing. Fixed embryos were stained with fluorescence-labelled antibodies against actin and tubulin, as well as DAPI for staining the nucleus. Labelled embryos were scanned using CLSM and images were analyzed with Q-Win software V3.
RESULTS: The fluorescence intensity of both vitrified and slow-frozen embryos was significantly lower for tubulin, actin, and nucleus as compared to non-cryopreserved embryos (p<0.001). Intensities of tubulin, actin, and nucleus in each stage were also decreased in vitrified and slow-frozen groups as compared to non-cryopreserved embryos.
CONCLUSIONS: Cryopreservation of mouse embryos by slow freezing had a more detrimental effect on the actin, tubulin, and nucleus structure of the embryos compared to vitrification. Vitrification is therefore superior to slow freezing in terms of embryonic cryotolerance.
MATERIALS AND METHODS: In this experimental study, female ICR mice (6-8 weeks old) were superovulated and cohabited with fertile males for 24 hours. Afterwards, their ovi- ducts were excised and embryos harvested. Embryos at the 2-cell stage were catego- rized as EC embryos, while zygotes with two pronuclei were categorized as LC embryos. Embryos were cultured in M16 medium supplemented with 3% bovine serum albumin (BSA) in a humidified 5% CO2atmosphere. Control embryos were cultured until the blastocyst stage without vitrification. Experimental embryos at the 2-cell stage were vitri- fied for one hour using 40% v/v ethylene glycol, 18% w/v Ficoll-70 and 0.5 M sucrose as the cryoprotectant. We recorded the numbers of surviving embryos from the control and experimental groups and their development until the blastocyst stage. Results were analyzed using the chi-square test.
RESULTS: A significantly higher proportion of EC embryos (96.7%) from the control group developed to the blastocyst stage compared with LC embryos (57.5%, P<0.0001). Similarly, in the experimental group, a significantly higher percentage of vitrified EC embryos (69.4%) reached the blastocyst stage compared to vitrified LC embryos (27.1%, P<0.0001).
CONCLUSION: Vitrified EC embryos are more vitrification tolerant than LC embryos. Prese- lection of EC embryos may be used as a tool for selection of embryos that exhibit higher developmental competence after vitrification.
METHODS: Female rats, once rendered hypothyroid via oral administration of methimazole (0.03% in drinking water) for twenty-one days were mated with fertile euthyroid male rats at 1:1 ratio. Pregnancy was confirmed by the presence of vaginal plug and this was designated as day-1. Thyroxine (20, 40 and 80 μg/kg/day) was then subcutaneously administered to pregnant, hypothyroid female rats for three days. A day after last injection (day four pregnancy), female rats were sacrificed and expression of thyroid hormone receptors (TR-α and β), retinoid X receptor (RXR) and extracellular signal-regulated kinase (ERK1/2) in uterus were quantified by Western blotting while their distribution in endometrium was visualized by immunofluorescence.
RESULTS: Expression of TRα-1, TRβ-1 and ERK1/2 proteins in uterus increased with increasing doses of thyroxine however no changes in RXR expression was observed. These proteins were found in the stroma with their distribution levels were relatively higher following thyroxine treatment.
CONCLUSIONS: Increased expression of TRα-1, TRβ-1 and ERK1/2 at day 4 pregnancy in thyroxine-treated hypothyroid pregnant rats indicate the importance of thyroxine in up-regulating expression of these proteins that could help mediate the uterine changes prior to embryo implantation.
MATERIAL AND METHODS: A) Effects of various doses of nicotine on in vitro embryonic development: Female mice were treated with 1.0, 3.0, or 5.0 mg/kg/day nicotine for 7 consecutive days. Animals were superovulated, cohabited overnight, and sacrificed. Embryos were cultured in vitro. Plasma was assayed. B) Effects of concomitant treatment of nicotine concurrently with various doses of gamma-TCT on in vitro embryonic development: Female mice were treated with nicotine (5.0 mg/kg/day), gavaged gamma-TCT of 30, 60, or 90 mg/kg/day or nicotine concurrently with gamma-TCT of 3 different doses for 7 consecutive days. Animals were superovulated, cohabited overnight, and sacrificed. Embryos were cultured and plasma was assayed.
RESULTS: A) Effects of various doses of nicotine on in vitro embryonic development: Number of hatched blastocysts decreased in 1.0 and 3.0 mg/kg/day nicotine groups. Nicotine at 5.0 mg/kg/day stopped embryo development at morula. MDA concentrations increased following all nicotine doses. B) Effects of concomitant treatment of nicotine concurrently with various doses of gamma-TCT on in vitro embryonic development: Embryo development was completed in all groups. MDA concentration increased only in the group treated with nicotine concurrently with 30 mg/kg/day gamma-TCT.
CONCLUSIONS: Nicotine impairs in vitro embryo development and increases MDA in plasma. The deleterious impact of nicotine on embryo development is reversed by supplementing gamma-TCT concurrently with nicotine.