Embryo wastage rates remain high in assisted reproductive technology (ART): a look at the trends from 2004-2013 in the USA

A Review: Biomechanical Aspects of the Fallopian Tube Relevant to its Function in Fertility

The fallopian tube (FT) plays a crucial role in the reproductive process by providing an ideal biomechanical and biochemical environment for fertilization and early embryo development. Despite its importance, the biomechanical functions of the FT that originate from its morphological aspects, and ultrastructural aspects, as well as the mechanical properties of FT, have not been studied nor used sufficiently, which limits the understanding of fertilization, mechanotrasduction, and mechanobiology during embryo development, as well as the replication of the FT in laboratory settings for infertility treatments. This paper reviews and revives valuable information on human FT reported in medical literature in the past five decades relevant to the biomechanical aspects of FT. In this review, we summarized the current state of knowledge concerning the morphological, ultrastructural aspects, and mechanical properties of the human FT. We also investigate the potential arising from a thorough consideration of the biomechanical functions and exploring often neglected mechanical aspects. Our investigation encompasses both macroscopic measurements (such as length, diameter, and thickness) and microscopic measurements (including the height of epithelial cells, the percentage of ciliated cells, cilia structure, and ciliary beat frequency). Our primary focus has been on healthy women of reproductive age. We have examined various measurement techniques, encompassing conventional metrology, 2D histological data as well as new spatial measurement techniques such as micro-CT.

Repeated cryopreservation process impairs embryo implantation potential but does not affect neonatal outcomes

RESEARCH QUESTION

Does repeated cryopreservation process affect embryo implantation potential and neonatal outcomes of human embryos?

DESIGN

This retrospective cohort study was conducted in the Reproductive Medicine Centre, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology. All assisted reproductive technology (ART) cycles were carried out between January 2014 and December 2018. Preferentially matched participants were divided into three groups according to the times of embryo cryopreservation: the fresh group (n = 249), the cryopreservation group (n = 244) and the re-cryopreservation group (n = 216). Embryo implantation rate, live birth rate, miscarriage rate and neonatal complication rate were compared among these three groups.

RESULTS

The embryo implantation rate, clinical pregnancy rate and live birth rate in the re-cryopreservation group were significantly lower, and the miscarriage rate also slightly increased. Logistic regression analysis indicated that embryos with repeated cryopreservation and lower trophectoderm scores were at higher risk of embryo implantation failure in single embryo transfer cycles (OR 1.79 and 1.56, respectively). No significant differences were observed in gender, gestational age, birthweight, neonatal abnormality and neonatal complications among the groups.

CONCLUSIONS

Our findings demonstrate the adverse effect of repeated cryopreservation on embryo implantation potential. The study offers embryologists and reproductive clinicians a warning of detrimental role of repeated cryopreservation. If unnecessary, it is strongly recommended to avoid repeated practice of vitrification and warming on embryos.

Spontaneous blastocyst collapse as an embryo marker of low pregnancy outcome: A Time-Lapse study

OBJECTIVE

In this study we investigate the correlation between spontaneous blastocyst collapse and pregnancy outcome.

METHODS

This is a retrospective study performed at Edinburgh Assisted Conception Programme, EFREC, Royal Infirmary of Edinburgh, UK. Embryos were cultured individually in 6.0% CO2, 5.0% O2, 89.0% N2, using single step medium (GTL™ Vitrolife, Göteborg, Sweden) and selected for transfer using standard morphological criteria. Using the EmbryoScope™ time-lapse monitoring (TLM), blastocysts collapse was analyzed by measuring the maximum volume reduction and defined as having collapsed if there was >50% volume reduction. Couples undergoing IVF/ICSI treatment and having an elective single embryo transfer (eSET) at blastocyst stage were included in this study. After the embryo transfer, retrospectively, each blastocyst was allocated to one of two groups (collapsed or not collapsed). 62 blastocysts collapsed once or more during development (17.4%), the remaining 294 showed no collapse (82.6%).

RESULTS

A significantly higher implantation rate (IR) of 61.2% and ongoing pregnancy rate (OPR) of 53.7% was observed when blastocysts which had not collapsed were replaced compared to cycles in which collapsed blastocysts were replaced (IR rate 22.6% and OPR 17.7%).

CONCLUSION

This study demonstrated that human blastocysts which collapse spontaneously during in vitro development are less likely to implant and generate a pregnancy compared with embryos which do not. Although this is a retrospective study, the results establish the utility of collapse episodes as new marker of embryo selection following eSET at blastocyst stage.

Mitochondrial DNA and genomic DNA ratio in embryo culture medium is not a reliable predictor for in vitro fertilization outcome

To investigate the ratio of mitochondrial DNA to genomic DNA (mt/gDNA) in embryo culture medium as a possible predictor for embryonic development and pregnancy outcome, we collected a total of 93 embryo biopsy specimens from 52 women at the corresponding Day 3 (D3) and Day 5 (D5) embryo culture medium of in vitro fertilization. With the multiple annealing and looping-based amplification cycles method of next-generation sequencing for whole genome amplification, we examined the karyotype of the biopsy samples and the mt/gDNA ratio in the culture medium. Results showed that the ratio of mt/gDNA had an upward trend with decreasing trophectoderm levels with no significant difference. At the same time, from D3 to D5, the mt/gDNA ratio in the medium of embryos that failed to become blastocysts showed an upward trend, and the mt/gDNA ratio of medium from embryos that reached blastulation with successful pregnancy showed a decreasing trend, but the differences were not statistically significant. We conclude that there is a certain correlation between mt/gDNA ratio and early embryonic development, but it does not reach a level that can be used as a clinical predictor.

Six-month recovery needed after dilation and curettage (D and C) for reproductive outcomes in frozen embryo transfer

In this study, the endometrial developmental and reproductive outcomes of frozen embryo transfers (FETs) which were performed subsequent to miscarriages managed by dilation and curettage (D and C) were investigated. The intracytoplasmic sperm injection (ICSI) blastocyst freeze-all cycles performed between January 2014 and August 2016 were screened for the patients who had undergone their FET (first), miscarriages (>5 < 14 weeks), D and C, and the patients who had undergone their FET (second) (study group; n = 71); and patients who underwent FET (1st), a chemical pregnancy loss (PL) (<5 weeks) and FET (2nd) (reference group; n = 38). The live births (LB; delivery >20 weeks) of FET (2nd) were analysed in two time-interval sub-groups: ≤6 months or >6 months. In the study and reference groups, the median endometrial thickness at the second FET of the ≤6 months sub-groups was found to be significantly reduced. The relative risk for LB was significantly higher (1.65 [0.994-2.723] p = .043) in the >6 months study sub-group, with a lower risk for PL (0.62 [0.268-1.427] p = .329), whereas, there were no significant differences between the reference sub-groups. The management of miscarriage with D and C results in a significant and transient decrease in reproductive function in subsequent FET. Impact Statement What is already known on this subject? Approximately, 15-30% of positive pregnancies in assisted reproductive technology (ART) end in biochemical pregnancy losses (PLs) or miscarriages. Cervical dilation with suction or blunt curettage (D and C), has been the procedure most often used to manage the retained products of conception (RPOC) after miscarriage. Intrauterine surgery has the potential to directly affect reproduction, depending on the endometrial impact. What the results of this study add? The endometrium after D and C surgery may require 6 months to recover normal reproductive function, in terms of both live birth and PL. The extent of the damage to endometrial function is not found to be reflected in the endometrial thickness. What the implications are of these findings for clinical practice and/or further research? Patients who undergo miscarriage after their ART treatment may need to delay further treatment for 6 months to optimise their chances of LB. Alternative miscarriage management procedures need to be investigated; procedures that have lower risks for an adverse reproductive function and allow for shorter time intervals between treatments.

Cumulative live birth and surplus embryo incidence after frozen-thaw cycles in PCOS: how many oocytes do we need?

PURPOSE

This study aimed to evaluate the cumulative live birth rate (CLBR) and surplus embryo rate of polycystic ovarian syndrome (PCOS) patients during in vitro fertilization and embryo transfer (IVF-ET) treatment.

METHODS

In this retrospective cohort study, we analyzed 1142 PCOS patients who underwent first IVF in our institution between January 2011 and December 2014. All patients were categorized into five groups according to the number of oocytes retrieved. Main outcomes include CLBR and surplus embryo rate.

RESULTS

A strong correlation was observed between number of oocytes retrieved and CLBR as well as surplus embryo rate in PCOS patients. CLBR was elevated with the increasing number of oocytes and plateaued when oocyte number was up to ten, whereas the surplus embryo rate steadily increased in line with the increase of oocyte number. Patients transferred with frozen embryos showed higher CLBR and LBR during first ET than patients transferred with fresh embryos.

CONCLUSIONS

For PCOS patients, retrieving more than ten oocytes leads to no significant benefit to CLBR but generates surplus embryos. Thus, moderate ovarian stimulation should be reconsidered during IVF treatment.