High proportion of immature oocytes in a cohort reduces fertilization, embryo development, pregnancy and live birth rates following ICSI

Late maturing oocyte rescue in poor-prognosis patients: delayed intracytoplasmic sperm injection results in more viable embryos

RESEARCH QUESTION

Can delayed intracytoplasmic sperm injection (DICSI) in late maturing oocytes improve fertilization, blastocyst formation, pregnancy and live birth rates for poor-prognosis patients?

DESIGN

Retrospective analysis of 2243 oocytes from 250 poor-prognosis patients who underwent 311 assisted reproductive technology (ART) cycles. Patients were offered DICSI to increase the number of embryos available for testing when over 50% of oocytes collected were immature on day 0, less than 50% of the injected oocytes were fertilized on day 1 or when patients were undergoing preimplantation genetic testing for aneuploidy.

RESULTS

Fertilization and blastulation rates differed depending on the original assessment of the oocyte maturation stage. Euploidy rate did not differ between blastocysts derived from fertilized oocytes originally assessed as metaphase I (MI) or metaphase II (MII). A transferred blastocyst derived from a matured oocyte originally assessed as MI was as likely to result in a live birth as one from a MII oocyte. No differences in delivery method, gestation period or birth weight were found between intracytoplasmic sperm injection and DICSI. As a result of DICSI, at least 27 cycles (8.7%), which would have otherwise been unproductive, resulted in live births, with five ongoing pregnancies.

CONCLUSIONS

Both MI and germinal vesicle oocytes can complete maturation in vitro. Blastocysts produced from these are likely to be chromosomally normal compared with oocytes originally assessed as MII, and result in similar live birth rates. With no differences in birth outcomes, and DICSI increasing overall ART cycle success, this approach has value for poor-prognosis patients.

Granulosa cell transcription is similarly impacted by superovulation and aging and predicts early embryonic trajectories

In vitro fertilization efficiency is limited in part because a fraction of retrieved oocytes fails to fertilize. Accurately evaluating their quality could significantly improve in vitro fertilization efficiency, which would require better understanding how their maturation may be disrupted. Here, we quantitatively investigate the interplay between superovulation and aging in mouse oocytes and their paired granulosa cells using a newly adapted experimental methodology. We test the hypothesis that superovulation disrupts oocyte maturation, revealing the key intercellular communication pathways dysregulated at the transcriptional level by forced hormonal stimulation. We further demonstrate that granulosa cell transcriptional markers can prospectively predict an associated oocyte's early developmental potential. By using naturally ovulated old mice as a non-stimulated reference, we show that aging and superovulation dysregulate similar genes and interact with each other. By comparing mice and human transcriptional responses of granulosa cells, we find that age-related dysregulation of hormonal responses and cell cycle pathways are shared, though substantial divergence exists in other pathways.

Expert opinion on refined and extended key performance indicators for individualized ovarian stimulation for assisted reproductive technology

OBJECTIVE

To assess the adequate ovarian follicular development and oocyte recovery between ovarian potential (antral follicle count [AFC]) before the start of ovarian stimulation (OS) and oocyte quantity and quality at oocyte retrieval. A holistic overview of the current key performance indicators (KPIs) was applied to identify the complementary strengths and identify where the current repertoire can be expanded.

DESIGN

Expert opinion.

INTERVENTION

None.

MAIN OUTCOME MEASURES

To formulate a proposal for a refined and expanded repertoire of KPIs for individualized OS for assisted reproductive technology.

RESULTS

The performance and outcomes of OS on ovarian follicular development can be evaluated through the application of defined KPIs. Current KPIs for OS are the ovarian sensitivity index, follicular output rate (FORT), oocyte retrieval rate, and follicle-to-oocyte index (FOI). Notably, there are no specific KPIs dedicated to the assessment of follicular development (i.e., recruitment, selection, growth, and dominance). In light of this, we recommend expanding the current KPIs for OS to include "early FORT" (accounting for the number of follicles measuring ≥10 to 11 mm on day 5/6 of OS relative to AFC) and "modified FORT" (the ratio between the number of follicles measuring ≥12 mm at the time of oocyte maturation triggering and AFC); the extension of oocyte retrieval rate to include two discrete categories at oocyte retrieval-follicles measuring ≥12 mm and ≥16 mm-to ensure that all responsive follicles are accounted for; and FOI to be measured at oocyte maturation triggering and oocyte retrieval ("advanced FOI").

CONCLUSION

Once validated and adopted in clinical practice, we envisage that the proposed expanded KPIs measuring the effect of OS on follicular development (recruitment, selection, growth, and dominance) will increase the understanding of the relationship between ovarian reserve, measured by AFC, and oocyte quantity and quality at oocyte retrieval. This understanding will enable physicians to better evaluate the direct effect of different gonadotropins and doses on ovarian response, leading to a more personalized approach to OS in the context of assisted reproductive technology treatment.

Oocyte maturation defect in women undergoing IVF: contributing factors and effects on mature sibling oocyte outcomes

PURPOSE

This study aimed to identify demographic and clinical factors associated with low maturation rates and to investigate if the rate of immature oocytes impacts the outcomes of mature sibling oocytes.

METHODS

Women undergoing their first IVF-ICSI cycle between 2018 and 2022 at a fertility clinic were included. Cycles were classified into five groups according to the proportion of Metaphase II stage oocytes (MII): Null (0% MII, n = 46), Poor (1-25% MII, n = 44), Low (26-50% MII, n = 453), Acceptable (51-75% MII, n = 1641), and Optimal (76-100% MII, n = 2642). Demographic characteristics and clinical outcomes were compared between the five groups. In patients with a Null/Poor maturation rate, subsequent cycle outcomes were also evaluated.

RESULTS

A total of 4826 cycles were included in the study; 69,909 oocytes were recovered, and 53,065 were MIIs (75.9%). The Null group was older, had lower levels of anti-Müllerian hormone (AMH), needed more gonadotropins and days of stimulation, had higher follicle stimulating hormone (FSH) levels on day 3, and had less follicles > 15 mm on the day of trigger. When the outcomes of mature oocytes were compared, fertilization, usable blastocyst, aneuploidy, and life birth rates were comparable among groups. A binary logistic regression model using number of oocytes, paternal age, and trigger type with live birth rate endpoint found no differences between the categories and the base line Poor category. When patients whose maturation rate was Null/Poor, 42 (47.0%) carried out a second cycle; the maturation rate increased (56.9 ± 31.5 vs. 11.6 ± 11.2%, P < 0.0001).

CONCLUSION

Our data suggest that poor responders are more likely to have low rates of oocyte maturation. The proportion of immature oocytes does not impact the outcomes of mature sibling oocytes. In patients with Null/Poor maturation in their first cycle, the subsequent cycle is often associated with improved maturation rates.

A blastocyst's implantation potential is linked to its originating oocyte cohort's blastulation rate: evidence for a cohort effect

OBJECTIVE

To investigate if blastocysts originating from different follicular cohorts have variable implantation rates, adjusted for oocyte age, morphology, and/or ploidy.

DESIGN

Retrospective cohort.

SETTING

Academic center.

PATIENT(S)

Patients who underwent one or more cycles of autologous ovarian stimulation and in vitro fertilization/intracytoplasmic sperm injection, followed by elective single frozen blastocyst transfer.

INTERVENTION(S)

Blastocyst progression rate of a follicular cohort; defined as the total number of the expanded blastocyst, euploid blastocyst, day 5 blastocyst, or day 5 euploid blastocyst(s) divided by the number of two pronuclei zygote(s).

MAIN OUTCOME MEASURE(S)

Implantation, defined as serum human chorionic gonadotropin >5 mIU/mL after elective single embryo transfer.

RESULT(S)

A total of 4,292 blastocysts were tracked from their follicular cohort origin to their outcome after elective single embryo transfer. The mean age ± standard deviation of the study population was 36.2 ± 3.6 years old. The median (interquartile range [IQR]) number of oocytes and two pronuclei zygotes per cohort was 17 (12-24) and 11 (8-16), respectively. The median (IQR) number of total expanded blastocysts and day 5 blastocysts per cohort was 6 (4-9) and 2 (1-4), respectively. Preimplantation genetic testing for aneuploidy utilization rate was 63.0%. The median (IQR) number of total euploid blastocysts and day 5 euploid blastocysts were 2 (1-4) and 1 (0-2), respectively. Median (IQR) overall blastocyst progression rate was 60.0% (43.5%-75.0%), euploid blastocyst progression rate 21.4% (13.3%-33.3%), day 5 blastocyst progression rate 20.0% (8.7%-35.2%), and day 5 euploid blastocyst progression rate 9.1% (0.0%-18.2%). All blastocyst progression parameters inversely correlated with increasing age. Multivariable mixed-effects logistic regression analyses, adjusting for oocyte age, number of oocytes retrieved, embryo morphology, and preimplantation genetic testing for aneuploidy status, showed a positive association between overall blastocyst progression (adjusted odds ratio [aOR], 1.04; 95% confidence interval [CI], 1.01-1.08), day 5 blastocyst progression (aOR, 1.05; 95% CI, 1.01-1.09), and day 5 euploid blastocyst progression (aOR, 1.10; 95% CI, 1.03-1.18) and implantation rates.

CONCLUSION(S)

Adjusting for age, oocytes retrieved, morphology, and ploidy status, blastocysts from follicular cohorts with high blastocyst progression rates demonstrate superior implantation potential compared with those from cohorts with lower blastocyst progression rates. This observation suggests the presence of a cohort effect, and offers valuable information for patient counseling on an embryo's implantation potential beyond ploidy/morphology.

Stereological study of organelle distribution in human mature oocytes

The ultrastructure of human oocytes has been described only qualitatively. To offer a precise organelle spatial distribution and organelle volume during the main maturation stages, we previously conducted stereological studies on prophase-I (GV) and metaphase-I (MI) oocytes, and here we present results on metaphase-II (MII) oocytes. Five donor oocytes from different donors were processed for transmission electron microscopy, and quantification of organelle distribution was performed using point-counting stereology. Statistical tests compared the means of the relative volumes occupied by organelles among oocyte regions. The most abundant organelles were elements of the smooth endoplasmic reticulum (SER), such as SER small vesicles, SER medium vesicles, SER large vesicles and SER isolated tubules, along with mitochondria, followed by SER tubular aggregates, cortical vesicles and lysosomes. Significant differences between oocyte regions were found for lysosomes, cortical vesicles and SER large vesicles. Comparisons of MII oocytes to previous findings in GV and MI oocytes evidenced specific patterns of organelle distribution and relative volumes. This final evaluation thus enables to track organelle spatial reorganization across oocyte stages, which, in addition to gathered knowledge, may be useful to assist in improvements of stimulation protocols, in-vitro maturation media and cryopreservation techniques.

The impact of low oocyte maturity ratio on blastocyst euploidy rate: a matched retrospective cohort study

OBJECTIVE

To investigate the association between a low oocyte maturity ratio from in vitro fertilization cycle and blastocyst euploidy.

METHODS

A total of 563 preimplantation genetic testing (PGT) cycles (PGT cycles with chromosomal structural rearrangements were excluded) were performed between January 2021 and November 2022 at our center (average oocyte maturity rate: 86.4% ± 14.6%). Among them, 93 PGT cycles were classified into the low oocyte maturity rate group (group A, < mean - 1 standard deviation [SD]), and 186 PGT cycles were grouped into the average oocyte maturity rate group (group B, mean ± 1 SD). Group B was 2:1 matched with group A. Embryological, blastocyst ploidy, and clinical outcomes were compared between the two groups.

RESULTS

The oocyte maturity (metaphase II [MII oocytes]), MII oocyte rate, and two pronuclei (2PN) rates were significantly lower in group A than in group B (5.2 ± 3.0 vs. 8.9 ± 5.0, P = 0.000; 61.6% vs. 93.0%, P = 0.000; 78.7% vs. 84.8%, P = 0.002, respectively). In group A, 106 of 236 blastocysts (44.9%) that underwent PGT for aneuploidy were euploid, which was not significantly different from the rate in group B (336/729, 46.1%, P = 0.753). However, euploid blastocysts were obtained only in 55 cycles in group A (55/93, 59.1%), which was lower than the rate in group B (145/186, 78.0%, P = 0.001). The clinical pregnancy rate in group B (73.9%) was higher than that in group A (58.0%) (P = 0.040).

CONCLUSION

Our results suggest that a low oocyte maturity ratio is not associated with blastocyst euploidy but is associated with fewer cycles with euploid blastocysts for transfer, lower 2PN rates, and lower clinical pregnancy rates.

Progesterone levels on hCG day and oocyte maturation in a Mexican IVF program

OBJECTIVE

Does progesterone levels on hCG day influence maturation rates and number of mature oocytes during ovarian stimulation for IVF/ICSI cycles?.

METHODS

A retrospective, observational, analytic, cross-sectional and cohort study was performed at the Reproductive Endocrinology Department of the Centro Médico Nacional 20 de Noviembre in Mexico City between 2015 to 2020. All female patients underwent an ovarian stimulation cycle for IVF/ICSI, either with a mild or conventional stimulation protocol. Patients were classified according to their progesterone levels, Group 1 <1.5ng/ml and Group 2 >1.5mg/ml. A Spearman Rho test, a simple linear regression model, a Principal Component Analysis and a Student's T-test, were performed.

RESULTS

A total of 600 patients were included. The overall results showed that there is a positive correlation between the number of retrieved, mature oocytes and progesterone levels on HCG day. After the Principal Component Analysis we observed that poor ovarian responders had the lowest maturation rate and number of mature oocytes. While the Student's t test showed that progesterone levels beyond 1.5ng/ml are associated to a higher number of mature oocytes but not a better maturation rate.

CONCLUSIONS

Higher serum progesterone levels are associated with increased retrieved and mature oocytes in high responders. At the same time, higher progesterone levels in lower responders are not associated with optimal ovarian response.

Embryology with precision: effective quality control in the in vitro fertilization laboratory

The purpose of this review is to address the critical need for standardization and clarity in the use of key performance indicators (KPIs) within the realm of in vitro fertilization (IVF), particularly emphasizing the integration of preimplantation genetic testing (PGT) processes. This review is timely and relevant given the persistently modest success rates of IVF treatments, which stand at approximately 30%, and the growing complexity of IVF procedures, including PGT practices. The review synthesizes recent findings across studies focusing on technical and clinical KPIs in embryology and genetic laboratories, identifying gaps in current research and practice, particularly the lack of standardized KPIs and terminology. Recent findings highlighted include the critical evaluation of technical KPIs such as Intracytoplasmic Sperm Injection (ICSI) fertilization rates, embryo development rates, and laboratory performance metrics, alongside clinical KPIs like the proportion of mature oocytes and clinical pregnancy rates. Notably, the review uncovers a significant gap in integrating and standardizing KPIs for PGT applications, which is essential for improving IVF outcomes and genetic diagnostic accuracy. The implications of these findings are profound for both clinical practice and research. For clinical practice, establishing a standardized set of KPIs, especially for PGT, could significantly enhance the success rates of IVF treatments by providing clearer benchmarks for quality and performance. For research, this review underscores the necessity for further studies to close the identified gaps, promoting a more integrated and standardized approach to KPIs in IVF and PGT processes. This comprehensive approach will not only aid in improving clinical outcomes but also in advancing the field of reproductive medicine.

Could the presence and proportion of three/multiple pronuclei (3PN/MPN) zygotes indicate the cytoplasmic maturation state of oocyte cohort in conventional IVF patients?

Although abnormally fertilized zygotes with three or multiple pronuclei (3 PN/MPN) are commonly believed to be associated with improper maturation of the oocyte cytoplasm in conventional IVF cycles, no studies investigated the association between the proportion of MPN zygotes and the maturation state of the oocyte cohort. We compared the cytoplasmic maturity of oocytes from conventional IVF cycles with different proportions of 3 PN/MPN zygotes. A total of 1428 conventional IVF patients with ≥6 oocytes retrieved and fresh embryos transferred were divided into 4 groups according to the proportions of 3 PN/MPN zygotes. The pregnancy outcomes and the proportion of nuclear immature oocytes were analyzed to suggest the cytoplasmic maturation state of the oocyte cohort. Our results showed that the group with a low proportion of 3 PN/MPN zygotes had a higher clinical pregnancy rate (CPR) than those without 3 PN/MPN zygotes (P < 0.05). However, the live birth rate (LBR) was not significantly different between the two groups. The implantation rate (IR), CPR, and LBR did not differ between the low-proportion and high-proportion 3 PN/MPN groups. The proportion of nuclear immature oocytes on day 1 was highest in the group without 3 PN/MPN zygotes (23.8 %) and gradually decreased with an increased proportion of 3 PN/MPN zygotes (P < 0.001). Therefore, the presence of 3 PN/MPN zygotes after conventional IVF may indicate a more mature cytoplasmic state of the oocyte cohort, and the increased proportion of 3 PN/MPN zygotes is associated with an increased maturation state of the whole oocyte cohort. The occurrence and proportion of 3 PN/MPN zygotes may serve as an indicator for the cytoplasmic maturity of the oocyte cohort and help clinicians evaluate the efficiency of ovarian stimulation and optimize the stimulation protocols in subsequent cycles.

The Effect of Wharton's Jelly-Derived Conditioned Medium on the In Vitro Maturation of Immature Oocytes, Embryo Development, and Genes Expression Involved in Apoptosis

Oocyte cytoplasmic maturation is a crucial process during in vitro maturation (IVM), and finding an appropriate IVM medium that promotes oocyte competence is very critical in assisted reproductive technology (ART). The aim of this study was to investigate the effects of umbilical cord Wharton's jelly (WJ-MSCs)-derived conditioned media on the maturation of immature oocytes and their developmental potential in humans after IVM, as well as apoptotic gene expression. A total of 392 germinal vesicle (GV) oocytes were collected from 207 women aged 25-35 years and divided into two IVM groups: (1) control group, which was cultured in CleavTM medium, and (2) experimental group, which was cultured in supernatants of umbilical cord Wharton's jelly as a conditioned medium (CM). First, WJ-MSCs were isolated, and their purity was analyzed. The immunophenotypes of WJ-MSCs were analyzed by flow cytometry. The quantitative expression of BCL2, BAX, and BAG1 in matured oocytes and embryos was evaluated through quantitative real-time polymerase chain reaction (qRT-PCR). Our findings showed that WJ-MSCs have a high proliferating capacity. The purity of the isolated cells was further validated by immunophenotyping, which revealed that their surface antigen expression had phenotypical properties similar to WJ-MSCs. When compared to CD34 and CD45 surface markers, the enlarged cells were positive for CD90, CD105, and CD44. There were significant differences in cytoplasmic maturation of oocytes and embryo quality between the two groups. The mRNA expression levels of BCL-2, BAG1, and BAX in matured oocytes and embryos were also significantly different between the two groups. Therefore, WJ-MSCs medium indicated potential efficacy in terms of ameliorating oocyte maturation and in promoting the development and genes expression of BAX, BCL-2, and BAG1.

Factors associated with the efficacy of mature oocyte production after dual-trigger controlled ovarian stimulation using a GnRH antagonist protocol

BACKGROUND

The number of mature oocytes retrieved plays a significant role in determining embryo development and pregnancy outcomes of in vitro fertilization (IVF). However, studies investigating factors predictive of the efficacy of mature oocyte production (EMOP) after dual-trigger controlled ovarian stimulation (COS) are rare. This study aims to identify key predictors of EMOP during dual-trigger COS with a gonadotropin-releasing hormone (GnRH) antagonist protocol for IVF.

METHODS

This retrospective cohort study included 359 first-time IVF patients undergoing dual-trigger COS with a GnRH antagonist protocol. EMOP was defined as the ratio of metaphase II (MII) oocyte count to antral follicle count (AFC). Based on EMOP results, patients were divided into two groups: group A (EMOP <70%; n = 232) and group B (EMOP ≥70%; n = 127).

RESULTS

Multivariate logistic regression analysis revealed that day-2 follicle-stimulating hormone (FSH), stimulation duration, and total oocyte count were the most significant predictors of EMOP ( p < 0.05; odds ratios: 1.637, 3.400, and 1.530, respectively). Receiver operating characteristic analysis demonstrated that total oocyte count <9.5 (area under the curve [AUC], 0.782; sensitivity, 76.2%; specificity, 69.2%; p < 0.001) and stimulation duration <9.5 days (AUC, 0.725; sensitivity, 63.5%; specificity, 66.7%; p < 0.001) significantly predicted EMOP <70%. Stimulation duration combined with total oocyte count exhibited the highest power in predicting EMOP <70% (AUC, 0.767; sensitivity, 92.3%; specificity, 42.4%).

CONCLUSION

Stimulation duration combined with total oocyte count was identified as the most important factor associated with the EMOP during dual-trigger COS in IVF using a GnRH antagonist protocol.

The developmental potential of mature oocytes derived from rescue in vitro maturation

OBJECTIVE

To examine the developmental competence of immature oocytes in stimulated cycles, that matured after rescue in vitro maturation (IVM) compared with their sibling in vivo matured oocytes.

DESIGN

Retrospective cohort study.

SETTING

IVF clinic.

PATIENTS

A total of 182 patients underwent 200 controlled ovarian stimulation cycles with intracytoplasmic sperm injection cycles in which immature oocytes were retrieved and at least one mature oocyte was obtained through rescue IVM.

INTERVENTION

In vitro culture of immature germinal vesicle (GV) and metaphase I (MI) oocytes, retrieved in stimulated cycles.

MAIN OUTCOME MEASURES

Fertilization rate, cleavage rate, blastulation rate, ploidy of embryos evaluated using preimplantation genetic testing for aneuploidy, morphokinetic parameters and pregnancy outcomes.

RESULTS

In total, 2,288 oocytes were retrieved from 200 cycles. After denudation, 1,056 of the oocytes (46% ± 16%) were classified as metaphase II (MII). A total of 333/375 (89%) of MI oocytes and 292/540 (54%) of GV oocytes matured overnight and underwent intracytoplasmic sperm injection. The fertilization rates of matured oocytes from MI rescue IVM (R-MI) and from GV rescue IVM (R-GV) were comparable with those of their sibling MII oocytes (71% vs. 66%; 66% vs. 63%, respectively). Early cleavage rates (80% ± 35% vs. 92% ± 20%; 80% ± 42% vs. 95% ± 28%, respectively) and blastulation rates (32 ± 40% vs. 62 ± 33%; 24 ± 37% vs. 60 ± 35%, respectively) were significantly decreased in rescue IVM matured oocytes (R-oocytes)-derived zygotes, but the blastocyst (BL) euploidy rate and "good quality" BL rate were comparable with those of MII sibling-derived embryos. In addition, rescue IVM embryos showed significantly higher levels of multinucleation at the 2- and 4-cell stages, as well as higher rates of zygote direct cleavage from one to 3 to 4 cells. Overall, 21 transfers of rescue IVM embryos resulted in 3 healthy live births.

CONCLUSIONS

For patients with a low maturation rate and/or low numbers of mature oocytes at retrieval, rescue IVM may contribute more competent oocytes and additional viable BLs for transfer from the same stimulation cycle, maximizing the chances for pregnancy and live birth.

Associations between Urinary Concentrations of Disinfection Byproducts and in Vitro Fertilization Outcomes: A Prospective Cohort Study in China

BACKGROUND

Experimental studies show that disinfection byproducts (DBPs) can inhibit oocyte maturation, decrease fertilization capacity, and impair embryo development, but human evidence is lacking.

OBJECTIVES

We aimed to evaluate the associations between exposure to drinking water DBPs and in vitro fertilization (IVF) outcomes.

METHODS

The study included 1,048 women undergoing assisted reproductive technology (ART) treatment between December 2018 and January 2020 from a prospective cohort study, the Tongji Reproductive and Environmental study in Wuhan, China. Exposure to DBPs was assessed by dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) in up to four urine samples, which were collected on the day of both enrollment and oocyte retrieval. Multivariable generalized linear mixed models, accounting for multiple IVF cycles per woman, were applied to evaluate the associations between urinary biomarkers of DBP exposures and IVF outcomes. Stratified analyses were used to explore the potential effect modifiers.

RESULTS

The included 1,048 women underwent 1,136 IVF cycles, with 960 (91.6%), 84 (8.0%), and 4 (0.4%) women contributing one cycle, two cycles, and three cycles, respectively. We found that elevated quartiles of urinary DCAA and TCAA concentrations were associated with reduced numbers of total oocytes and metaphase II oocytes and that urinary DCAA concentrations with a lower proportion of best-quality embryos (all p for trends < 0.05 ). Moreover, elevated quartiles of urinary DCAA concentrations were associated with decreased proportions of successful implantation, clinical pregnancy, and live birth (14%, 15%, and 15% decreases in adjusted means comparing the extreme quartiles, respectively; all p for trends < 0.05 ). Stratification analyses showed that the inverse associations of urinary TCAA concentrations with multiple IVF outcomes were stronger among women ≥ 30 y of age (p for interactions < 0.05 ).

DISCUSSION

Exposure to drinking water DBPs was inversely associated with some IVF outcomes among women undergoing ART treatment. Further study is necessary to confirm our findings. https://doi.org/10.1289/EHP12447.

Clinical and laboratory key performance indicators in IVF: A consensus between the Italian Society of Fertility and Sterility and Reproductive Medicine (SIFES-MR) and the Italian Society of Embryology, Reproduction and Research (SIERR)

PURPOSE

Infertility is increasing worldwide, and many couples seek IVF. Clinical management and laboratory work are fundamental in the IVF journey. Therefore, the definition of reliable key performance indicators (KPIs) based on clinical and laboratory parameters, is essential for internal quality control (IQC). Laboratory performance indicators have been identified and a first attempt to also determine clinical ones has been recently published. However, more detailed indicators are required.

METHODS

An Italian group of experts in Reproductive Medicine from both public and private clinics on behalf of SIFES-MR and SIERR was established to define IVF indicators to monitor clinical performance.

RESULTS

The working group built a consensus on a list of KPIs, performance indicators (PIs) and recommendation indicators (RIs). When deemed necessary, the reference population was stratified by woman age, response to ovarian stimulation and adoption of preimplantation genetic testing for aneuploidies (PGT-A). Each indicator was scored with a value from 1 to 5 and a weighted average formula - considering all the suggested parameters-was defined. This formula generates a center performance score, indicating low, average, good, or excellent performance.

CONCLUSION

This study is intended to provide KPIs, PIs and RIs that encompass several essential aspects of a modern IVF clinic, including quality control and constant monitoring of clinical and embryological features. These indicators could be used to assess the quality of each center with the aim of improving efficacy and efficiency in IVF.

Assisted gamete treatment to pinpoint acquired meiotic maturity and overcome oocyte activation deficiency contributed by both gametes

Objective

To treat couples with total fertilization failure (TFF) based on a combined oocyte- and sperm-related oocyte activation deficiency by optimizing oocyte response to chemical activation with calcium ionophore.

Design

Case report.

Setting

Tertiary Hospital.

Patients

Two couples with a history of TFF after intracytoplasmic sperm injection intracytoplasmic sperm injection (ICSI).

Interventions

To overcome oocyte-related oocyte activation deficiency (OAD), extended in vivo/in vitro oocyte maturation was performed to enhance ooplasmic maturity; to address sperm-related OAD, assisted gamete treatment (AGT) was performed to trigger oocyte activation.

Main outcome measures

Treatment cycle outcomes for the 2 couples undergoing ICSI with extended oocyte maturation (EOM) and AGT.

Results

We identified 2 couples with TFF after ICSI because of a combined factor of OAD confirmed by phospholipase C zeta expression and genomic assessment. Initial AGT treatment alone failed to enhance fertilization, suggesting superimposed oocyte dysmaturity prohibiting oocytes from responding to chemical stimuli. To address this complex form of OAD, in couple 1, 27 oocytes out of 34 retrieved presented normal metaphase II spindles after EOM; ICSI with AGT yielded a fertilization rate of 63.0% (17/27). All 17 zygotes were cryopreserved initially. Two embryos were thawed and transferred, yielding a monochorionic diamniotic twin pregnancy. Couple 2 underwent 3 ICSI cycles with EOM and AGT; 91.4% (32/35) of oocytes displayed normal metaphase II spindle and achieved an overall fertilization rate of 43.8% (14/32). A total of 12 blastocysts were cryopreserved. A single 46XY blastocyst was thawed and transferred, resulting in a singleton pregnancy.

Conclusions

Our study has demonstrated the usefulness of EOM by targeting spindle presence to enhance chemical responses to AGT.

Combining Machine Learning with Metabolomic and Embryologic Data Improves Embryo Implantation Prediction

This study investigated whether combining metabolomic and embryologic data with machine learning (ML) models improve the prediction of embryo implantation potential. In this prospective cohort study, infertile couples (n=56) undergoing day-5 single blastocyst transfer between February 2019 and August 2021 were included. After day-5 single blastocyst transfer, spent culture medium (SCM) was subjected to metabolite analysis using nuclear magnetic resonance (NMR) spectroscopy. Derived metabolite levels and embryologic parameters between successfully implanted and failed groups were incorporated into ML models to explore their predictive potential regarding embryo implantation. The SCM of blastocysts that resulted in successful embryo implantation had significantly lower pyruvate (p<0.05) and threonine (p<0.05) levels compared to medium control but not compared to SCM related to embryos that failed to implant. Notably, the prediction accuracy increased when classical ML algorithms were combined with metabolomic and embryologic data. Specifically, the custom artificial neural network (ANN) model with regularized parameters for metabolomic data provided 100% accuracy, indicating the efficiency in predicting implantation potential. Hence, combining ML models (specifically, custom ANN) with metabolomic and embryologic data improves the prediction of embryo implantation potential. The approach could potentially be used to derive clinical benefits for patients in real-time.

Higher miscarriage rate in subfertile women with endometriosis receiving unbiopsied frozen-warmed single blastocyst transfers

Background: Assisted reproductive technology treatment is recommended to overcome endometriosis-associated infertility but current evidence is controversial. Endometriosis is associated with lower antral follicle count (AFC) and oocyte yield but similar clinical outcomes compared to controls. Unaffected ovarian stimulation response and embryological outcomes but lower clinical pregnancy and live birth rates and higher miscarriage rates have been reported, implying direct impact on endometrial receptivity. With evidence emerging on the benefit of frozen-warmed and blastocyst stage transfer, we investigated ART outcomes in endometriosis using homogeneous case-control groups. Methods: This is a retrospective observational case-control study including n = 66 frozen-warmed unbiopsied single blastocyst transfers of patients with endometriosis and n = 96 of women exhibiting idiopathic sterility. All frozen-warmed transfers followed artificial endometrial preparation. Results: In control women, the mean number of oocytes recovered at oocyte pick up was higher compared to women with endometriosis (15.3 ± 7.1 vs. 12.7 ± 5.2, p = 0.025) but oocyte maturation index (mature oocytes/total oocytes at oocyte pick up) was significantly higher for endometriosis (48.2% vs. 34.0%, p = 0.005). The same was shown for the subgroup of 44 endometriosis patients after endometrioma surgery when compared with controls (49.1% vs. 34.0%, p = 0.014). Clinical pregnancy rate was not higher in endometriosis but was close to significance (47.0% vs. 32.3%, p = 0.059) while live birth rate was comparable (27.3% vs. 32.3%, p = 0.746). Miscarriage rate was higher in the endometriosis group (19.7% vs. 7.3%, p = 0.018). A significantly higher AFC was observed in the control group in comparison with the endometriosis group (16.3 ± 7.6 vs. 13.4 ± 7.0, p = 0.014). Live birth rate did not differ when comparing all endometriosis cases (p = 0.746), ASRM Stage I/II and Stage III/IV (p = 0.348 and p = 0.888) with the control group but the overall pregnancy rate was higher in ASRM Stage I/II (p = 0.034) and miscarriage rate was higher in ASRM Stage III/IV (p = 0.030) versus control. Conclusion: Blastocyst transfers in women with endometriosis originate from cycles with lower AFC but higher share of mature oocytes than in control women, suggesting that endometriosis might impair ovarian reserve but not stimulation response. A higher miscarriage rate, independent of blastocyst quality may be attributed to an impact of endometriosis on the endometrium beyond the timing of implantation.

Low oocyte maturity ratio is associated with a reduced in vitro fertilization and intracytoplasmic sperm injection live birth rate

OBJECTIVE

To determine whether a low oocyte maturity ratio in a cohort of oocytes from an in vitro fertilization cycle predicts outcomes and to examine clinical factors associated with oocyte maturity.

DESIGN

A retrospective cohort study.

SETTING

An academic medical center.

INTERVENTION(S)

Determination of oocyte maturity immediately after the retrieval and 6 hours later if intracytoplasmic sperm injection was performed.

MAIN OUTCOME MEASURE(S)

The primary outcome was live birth rate after the first embryo transfer. Secondary outcomes included clinical pregnancy, miscarriage, and fertilization rates.

RESULT(S)

After adjusting for age, preimplantation genetic testing, and number of embryos transferred, we found that a low oocyte maturity ratio was associated with a decreased live birth rate (adjusted odds ratio [AOR], 0.41; 95% confidence interval [CI], 0.22-0.77) and clinical pregnancy rate (AOR, 0.32; 95% CI, 0.17-0.61). We did not find a relationship between oocyte maturity and miscarriage rate (AOR, 0.25; 95% CI, 0.03-1.91) or fertilization rate (Welch test). The number of 2 pronuclei embryos per retrieved oocyte was found to be associated with the maturity ratio at retrieval. Patients with anovulation had slightly reduced oocyte maturity compared with other diagnostic groups.

CONCLUSION(S)

Low oocyte maturity ratio is an important factor related to poor in vitro fertilization outcomes, including decreased pregnancy and live birth rates.

Rescue IVM of Denuded GV- and MI-Stage Oocytes of Premenopausal Rats with Oncostatin M, Insulin-like Growth Factor I, and Growth Hormone

Immature oocytes are retrieved and matured through in vitro maturation (IVM). Maturation, fertilization rates, and embryo development via IVM are all lower than those found in vitro fertilization (IVF) cycles. We investigated the effects of oncostatin M (OSM), insulin-like growth factor-1 (IGF-I), and growth hormone (GH) in rescue IVM. A total of 111 germinal vesicle (GV) and 17 metaphase I (MI) oocytes were obtained after conventional IVF from 28 female Wistar albino rats. Denuded immature oocytes were cultured in maturation medium supplemented with OSM, IGF-1, or GH. The quantities of metaphase II (MII) oocytes matured from the GV stage were 17 of 30 (56.6%), 15 of 28 (53.5%), 10 of 30 (33.3%), and 7 of 23 (30.3%), in control, OSM, IGF-I, and GH groups, respectively. Maturation rates in control and OSM groups were higher than those in IGF-I and GH groups (p = 0.001). The quantities of MII oocytes matured from MI stage were 7 of 7 (100%), 4 of 4 (100%), 1 of 1 (100%), and 1 of 5 (20%) in control, OSM, IGF-I, and GH groups, respectively. Maturation rates from MI to MII stages in control, OSM, and IGF-I groups were higher than those in the GH group (p = 0.004). Acceptable maturation rates are observed with OSM in rat oocytes in rescue IVM.

Oocyte quality and embryo selection strategies: a review for the embryologists, by the embryologists

With the advance of assisted reproduction techniques, and the trend towards blastocyst culture and single embryo transfer, gamete and embryo assessment have gained greater importance in ART treatment. Embryo quality depends mainly on gamete quality and culture conditions. Oocyte maturity identification is necessary in order to plan fertilization timing. Mature oocytes at the metaphase II stage show a higher fertilization rate compared to immature oocytes. Morphology assessment is a critical yet challenging task that may serve as a good prognostic tool for future development and implantation potential if done effectively. Various grading systems have been suggested to assess embryos at pronuclear, cleavage, and blastocyst stages. By identifying the embryo with the highest implantation potential, it is possible to reduce the number of embryos transferred without compromising the chances of a successful pregnancy. Apart from the conventional morphology assessment, there are several invasive or non-invasive methods for embryo selection such as preimplantation genetic testing, morphokinetics, proteomics, metabolomics, oxygen consumption, and measurement of oxidative stress in culture medium. Morphokinetics is a method based on time-lapse technology and continuous monitoring of embryos. In this review, we aim to describe and compare the most effective and widely used methods for gamete and embryo assessment as well as embryo selection.

Rescue in vitro maturation may increase the pregnancy outcomes among women undergoing intracytoplasmic sperm injection

INTRODUCTION

To investigate whether rescue in vitro maturation (R-IVM) improves the reproductive outcomes among women undergoing intracytoplasmic sperm injection (ICSI) after one oocyte retrieved cycle.

METHODS

Between January 2019 and December 2020, 2602 women who underwent ICSI in the Reproductive Medicine Center of Tongji Hospital, Wuhan, China, were included in our retrospective cohort study. There were 2112 women undergoing only ICSI and 490 women with R-IVM followed by ICSI. The intermediate reproductive outcomes and pregnancy outcomes were assessed, including the number of normally fertilized embryos, number of cleaved embryos, number of good-quality embryos, number of day-3 available embryos, number of embryos cultured past day-3, number of blastocysts, number of available blastocysts, biochemical pregnancy, miscarriage, clinical pregnancy and live birth. The perinatal outcomes were also assessed, including preterm birth and birth weight. The abovementioned outcomes were also calculated for in vivo matured and R-IVM oocytes separately in women undergoing ICSI with R-IVM group.

RESULTS

Compared with the women who underwent only ICSI, those who underwent ICSI with R-IVM had higher numbers of MII oocytes, normally fertilized embryos, cleaved embryos, day-3 available embryos, embryos cultured past day-3, and higher oocyte maturation rate, available embryo rate than women undergoing only ICSI. Additionally, we found that women undergoing ICSI with R-IVM had an increased chance of clinical pregnancy (adjusted OR=1.50, 95% CI: 1.17-1.93) and cumulative live birth (adjusted OR=1.35, 95% CI: 1.07-1.71). After propensity score matching (PSM), the cumulative live birth rate was 60.1% for women undergoing ICSI with R-IVM versus 54.9% for women undergoing only ICSI (OR=1.24, 95% CI: 0.94-1.63). The reproductive outcomes were also significantly different when calculated for in vivo matured and R-IVM oocytes separately in women undergoing ICSI with R-IVM group. All live births from R-IVM embryos were healthy and without malformations or complications.

CONCLUSION

R-IVM may improve the reproductive outcomes of women undergoing ICSI. It may also provide a reference for the safety of R-IVM. This study maybe support a routine application of R-IVM among patients who intend to undergo ICSI.

Prediction of ovarian response in IVF/ICSI cycles

Objective:

Our study aims to evaluate the various correlations between demographic, biochemical, ultrasound, and ovarian stimulation parameters with the percentage of mature oocytes in conventional stimulation for IVF/ICSI cycles in order to develop a predictive model to improve our understanding of the oocyte maturation process.

Methods:

This is a retrospective cohort study; patients underwent conventional antagonist ovarian stimulation protocols for fresh IVF/ICSI cycles. A total of 256 IVF/ICSI cycles were included. Age, antral follicle count (AFC), baseline serum follicle-stimulating hormone (FSH) levels, baseline serum luteinizing hormone (LH) levels, baseline serum estradiol (E2) levels, peak estradiol, P4 on hCG day, the body mass index (BMI), and stimulation length were measured. The variables were tested for correlations with the number of retrieved oocytes (#RO) and the number of mature oocytes (#MO). A backward stepwise regression was performed to identify the variables that correlated more strongly with percentage of mature oocytes (%MO).

Results:

A predictive equation was obtained with the variables that were not excluded in the model. % MO = 72.700 - 0.910 (Age) + 0.979 (BMI) + 1.209 (Baseline serum LH) - 0.647 (Progesterone on human Chorionic Gonadotropin day).

Conclusions:

We concluded that age, the BMI, baseline serum LH, and progesterone level on hCG day may predict %MO. Prospective studies are required to validate this predictive equation.

Single-cell RNA sequencing identifies molecular targets associated with poor in vitro maturation performance of oocytes collected from ovarian stimulation

STUDY QUESTION

What is the transcriptome signature associated with poor performance of rescue IVM (rIVM) oocytes and how can we rejuvenate them?

SUMMARY ANSWER

The GATA-1/CREB1/WNT signalling axis was repressed in rIVM oocytes, particularly those of poor quality; restoration of this axis may produce more usable rIVM oocytes.

WHAT IS KNOWN ALREADY

rIVM aims to produce mature oocytes (MII) for IVF through IVM of immature oocytes collected from stimulated ovaries. It is not popular due to limited success rate in infertility treatment. Genetic aberrations, cellular stress and the absence of cumulus cell support in oocytes could account for the failure of rIVM.

STUDY DESIGN, SIZE, DURATION

We applied single-cell RNA sequencing (scRNA-seq) to capture the transcriptomes of human in vivo oocytes (IVO) (n = 10) from 7 donors and rIVM oocytes (n = 10) from 10 donors. The effects of maternal age and ovarian responses on rIVM oocyte transcriptomes were also studied. In parallel, we studied the effect of gallic acid on the maturation rate of mouse oocytes cultured in IVM medium with (n = 84) and without (n = 85) gallic acid.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Human oocytes were collected from donors aged 28-41 years with a body mass index of <30. RNA extraction, cDNA generation, library construction and sequencing were performed in one preparation. scRNA-seq data were then processed and analysed. Selected genes in the rIVM versus IVO comparison were validated by quantitative real-time PCR. For the gallic acid study, we collected immature oocytes from 5-month-old mice and studied the effect of 10-μM gallic acid on their maturation rate.

MAIN RESULTS AND THE ROLE OF CHANCE

The transcriptome profiles of rIVM/IVO oocytes showed distinctive differences. A total of 1559 differentially expressed genes (DEGs, genes with at least 2-fold change and adjusted P < 0.05) were found to be enriched in metabolic processes, biosynthesis and oxidative phosphorylation. Among these DEGs, we identified a repression of WNT/β-catenin signalling in rIVM when compared with IVO oocytes. We found that oestradiol levels exhibited a significant age-independent correlation with the IVO mature oocyte ratio (MII ratio) for each donor. rIVM oocytes from women with a high MII ratio were found to have over-represented cellular processes such as anti-apoptosis. To further identify targets that contribute to the poor clinical outcomes of rIVM, we compared oocytes collected from young donors with a high MII ratio with oocytes from donors of advanced maternal age and lower MII ratio, and revealed that CREB1 is an important regulator. Thus, our study identified that GATA-1/CREB1/WNT signalling was repressed in both rIVM oocytes versus IVO oocytes and in rIVM oocytes of lower versus higher quality. Consequently we investigated gallic acid, as a potential antioxidant substrate in human rIVM medium, and found that it increased the mouse oocyte maturation rate by 31.1%.

LARGE SCALE DATA

Raw data from this study can be accessed through GSE158539.

LIMITATIONS, REASONS FOR CAUTION

In the rIVM oocytes of the high- and low-quality comparison, the number of samples was limited after data filtering with stringent selection criteria. For the oocyte stage identification, we were unable to predict the presence of oocyte spindle, so polar body extrusion was the only indicator.

WIDER IMPLICATIONS OF THE FINDINGS

This study showed that GATA-1/CREB1/WNT signalling was repressed in rIVM oocytes compared with IVO oocytes and was further downregulated in low-quality rIVM oocytes, providing us the foundation of subsequent follow-up research on human oocytes and raising safety concerns about the clinical use of rescued oocytes.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the Collaborative Research Fund, Research Grants Council, C4054-16G, and Research Committee Funding (Research Sustainability of Major RGC Funding Schemes), The Chinese University of Hong Kong. The authors have no conflicts of interest to declare.

Developmental potential of immature human oocytes aspirated after controlled ovarian stimulation

PURPOSE

Intracytoplasmic sperm injection (ICSI) for initially immature oocytes that mature in vitro is controversial and practice varies widely. While it may increase the number of usable embryos, it may also be time-intensive and potentially low-yield. This study sought to elucidate which patients may benefit from ICSI of initially immature oocytes that matured in vitro.

METHODS

A retrospective study comparing fertilization, cleavage, blastulation, and embryo usage rates between sibling initially immature and mature oocytes that underwent ICSI between 2015 and 2019 was performed. Outcomes of initially immature oocytes were stratified by initial maturation stage, timing of progression to metaphase II (MII) in vitro, percentage of mature oocytes in the cycle, and female age.

RESULTS

Ten thousand eight hundred seventeen oocytes from 889 cycles were included. Of 3137 (29.0%) initially immature oocytes, 418 (13.3%) reached MII later on the day of retrieval (day 0) and 1493 (47.6%) on day 1. Overall, embryos originating from initially immature oocytes had lower cleavage and blastulation rates compared to those from initially mature oocytes (P<0.05, all groups). However, embryos from oocytes that matured later on day 0 comprised a unique subset that had clinically similar cleavage (75% vs 80%, RR 0.93, P=0.047) and blastulation rates (41% vs 50%, RR 0.81, P=0.024) compared to initially mature oocytes. Women with low percentages of mature oocytes in the cycle overall and women ≥40 in cleavage cycles derived the highest relative benefit from the use of immature oocytes.

CONCLUSION

ICSI of immature oocytes, particularly those that mature later on the day of retrieval, may improve numbers of usable embryos. This study supports routine reassessment of immature oocytes for progression to MII and ICSI on day 0. An additional reassessment on day 1 may also be of use in older women or those with low percentage of mature oocytes.

Monopronucleated (1PN) and tripronuclear (3PN) zygotes formation during assisted reproduction in POSEIDON group 4 patients: Emphasizing on polar bodies

AIM

Abnormal fertilization (1PN/3PN) and its accompanying polar body (PB) conditions have been less discussed in poor ovarian responders. By observing the PBs, we analyzed the mechanisms of abnormal fertilization and aimed to explore the role of intracytoplasmic sperm injection/in vitro fertilization (ICSI/IVF) in POSEIDON group 4 patients.

METHODS

An observational study. All fresh IVF/ICSI cycles from January 2018 to December 2019 were evaluated. The inclusion criteria were POSEIDON group 4. Fertilization and PB conditions were assessed 16-18 h post-insemination. Primary observation endpoints including normal fertilization, abnormal fertilization, and total fertilization failure rate.

RESULTS

A total of 351 cycles involving 180 patients met the inclusion criteria. Of these, 15 cycles reported no retrieved oocytes. Finally, 336 cycles (IVF, n = 267; ICSI, n = 69) were included. A total of 1005 oocytes and 939 embryos were assessed. The mean female age was 40.8 years, and the mean AMH level was 0.6 ng/mL. The normal fertilization rate was 69.7%. The zygote distribution was 18.7% 0PN, 3.9% 1PN, 66.9% 2PN, 9.5% 3PN, and 1.0% ≥4PN. For 1PN zygotes, 59% were denoted as 1PN2PB. The mean 3PN rate was 8.9%.

CONCLUSIONS

In POSEIDON group 4, most of the monopronucleated zygotes were 1PN2PB. Digyny (3PN1PB), due to failure to extrude the second PB, was the major cause of triploidy in which ICSI could not circumvent. The distribution of abnormally fertilized zygotes was similar in IVF and ICSI. To investigate the mechanisms of abnormal fertilization and assess whether ICSI is necessary, analysis of PB will provide important clues.

Single-center thorough evaluation and targeted treatment of globozoospermic men

Purpose

To characterize, by specific biomarkers and nucleic acid sequencing, the structural and genomic sperm characteristics of partial (PG) and complete globozoospermic (CG) men in order to identify the best reproductive treatment.

Methods

We assessed spermatozoa from 14 consenting men ultrastructurally, as well as for histone content, sperm chromatin integrity, and sperm aneuploidy. Additional genomic, transcriptomic, and proteomic evaluations were carried out to further characterize the CG cohort. The presence of oocyte-activating sperm cytosolic factor (OASCF) was measured by a phospholipase C zeta (PLCζ) immunofluorescence assay. Couples were treated in subsequent cycles either by conventional ICSI or by ICSI with assisted gamete treatment (AGT) using calcium ionophore (Ionomycin, 19657, Sigma-Aldrich, Saint Louis, MO, USA).

Results

Ultrastructural assessment confirmed complete acrosome deficiency in all spermatozoa from CG men. Histone content, sperm chromatin integrity, and sperm aneuploidy did not differ significantly between the PG (n = 4) and CG (n = 10) cohorts. PLCζ assessment indicated a positive presence of OASCF in 4 PG couples, who underwent subsequent ICSI cycles that yielded a 36.1% (43/119) fertilization with a 50% (2/4) clinical pregnancy and delivery rate. PLCζ assessment failed to detect OASCF for 8 CG patients who underwent 9 subsequent ICSI cycles with AGT, yielding a remarkable improvement of fertilization (39/97; 40.2%) (P = 0.00001). Embryo implantation (6/21; 28.6%) and clinical pregnancies (5/7; 71.4%) were also enhanced, resulting in 4 deliveries. Gene mutations (DPY19L2, SPATA16, PICK1) were identified in spermatozoa from CG patients. Additionally, CG patients unable to sustain a term pregnancy had gene mutations involved in zygote development (NLRP5) and postnatal development (BSX). CG patients who successfully sustained a pregnancy had a mutation (PIWIL1) related to sperm phenotype. PLCZ1 was both mutated and underexpressed in these CG patients, regardless of reproductive outcome.

Conclusions

Sperm bioassays and genomic studies can be used to characterize this gamete’s capacity to support embryonic development and to tailor treatments maximizing reproductive outcome.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10815-021-02191-4.

Thoughts on the popularity of ICSI

Purpose

Intracytoplasmic sperm injection (ICSI) is the most widely utilized assisted reproductive technique (ART) worldwide. In this feature, we review the early assisted fertilization attempts that eventually led to the development of ICSI, and discuss its current utilization in cases of male and non-male factor infertility.

Methods

We researched the literature related to the development, indications, and current use of ICSI, such as sperm structural abnormalities, male genetic indications, surgically retrieved sperm, high sperm chromatin fragmentation, oocyte dysmorphism, and preimplantation genetic testing (PGT). We also describe the potential future applications of ICSI.

Results

This review summarizes the early micromanipulation techniques that led to the inception of ICSI. We also explore its current indications, including non-male factor infertility, where its use is more controversial. Finally, we consider the benefits of future advancements in reproductive biology that may incorporate ICSI, such as in vitro spermatogenesis, neogametogenesis, and heritable genome editing.

Conclusion

The versatility, consistency, and reliability of ICSI have made it the most prevalently utilized ART procedure worldwide.

Identification and treatment of men with phospholipase Cζ-defective spermatozoa

OBJECTIVE

To identify and treat the gamete responsible for complete fertilization failure with intracytoplasmic sperm injection (ICSI) using a newly proposed assisted gamete treatment (AGT).

DESIGN

Prospective cohort study.

SETTING

Center for reproductive medicine.

PATIENT(S)

One-hundred and fourteen couples with an adequate number of spermatozoa for ICSI and a fertilization rate of ≤10%, after controlling for maternal age.

INTERVENTION(S)

Couples with an oocyte-related oocyte activation deficiency (OAD) underwent a subsequent cycle with a modified superovulation protocol; couples with sperm-related OAD had an additional genetic and epigenetic assessment to identify mutations and expression levels of the corresponding genes.

MAIN OUTCOME MEASURE(S)

Treatment cycle outcome for couples undergoing ICSI with either a modified superovulation protocol or AGT compared with their historical cycle.

RESULT(S)

A total of 114 couples matched the inclusion criteria, representing approximately 1.3% of the total ICSI cycles performed at our center, with age-matched controls. Fifty-two couples were confirmed negative for sperm-related OAD by the phospholipase Cζ (PLCζ) assay, indicating oocyte-related factors in their failed fertilization cycles. Couples were treated by one of two AGT protocols, AGT-initial or AGT-revised, in a subsequent attempt that was compared with their historical cycle. Subsequent ICSI cycles with a tailored superovulation protocol yielded significantly higher fertilization (59.0% vs. 2.1%) and clinical pregnancy (28.6% vs. 0) rates. In 24 couples (mean ± standard deviation: maternal age, 35.6 ± 5 years; paternal age, 39.8 ± 6 years) sperm-related OAD was confirmed; in four men, a deletion on the PLCZ1 gene was identified. Additional mutations were also identified of genes supporting spermiogenesis and embryo development (PIWIL1, BSX, NLRP5) and gene deletions confirming a complete absence of the subacrosomal perinuclear theca (PICK1, SPATA16, DPY19L). Subsequent AGT treatment provided higher fertilization (42.1%) and clinical pregnancy (36% vs. 0%) rates for couples with a history of impaired (9.1%) fertilization. A comparison of the two AGT protocols, AGT-initial or AGT-revised, revealed that the latter yielded even more favorable fertilization (37.6% vs. 45.9%) and clinical pregnancy (21.1% vs. 83.3%) rates.

CONCLUSION(S)

In couples with an oocyte-related OAD, tailoring the superovulation protocol resulted in successful fertilization, term pregnancies, and deliveries. In couples with a sperm-related OAD as determined by PLCζ assay, mouse oocyte activation test, and the assessment of gene mutations and function, AGT was successful. The AGT-revised protocol yielded an even higher fertilization rate than the AGT-initial protocol, resulting in the birth of healthy offspring in all couples who achieved a clinical pregnancy.