Opening the black box: why do euploid blastocysts fail to implant? A systematic review and meta-analysis.

BACKGROUND: A normal chromosomal constitution defined through PGT-A assessing all chromosomes on trophectoderm (TE) biopsies represents the strongest predictor of embryo implantation. Yet, its positive predictive value is not higher than 50-60%. This gap of knowledge on the causes of euploid blastocysts' reproductive failure is known as 'the black box of implantation'. OBJECTIVE AND RATIONALE: Several embryonic, maternal, paternal, clinical, and IVF laboratory features were scrutinized for their putative association with reproductive success or implantation failure of euploid blastocysts. SEARCH METHODS: A systematic bibliographical search was conducted without temporal limits up to August 2021. The keywords were '(blastocyst OR day5 embryo OR day6 embryo OR day7 embryo) AND (euploid OR chromosomally normal OR preimplantation genetic testing) AND (implantation OR implantation failure OR miscarriage OR abortion OR live birth OR biochemical pregnancy OR recurrent implantation failure)'. Overall, 1608 items were identified and screened. We included all prospective or retrospective clinical studies and randomized-controlled-trials (RCTs) that assessed any feature associated with live-birth rates (LBR) and/or miscarriage rates (MR) among non-mosaic euploid blastocyst transfer after TE biopsy and PGT-A. In total, 41 reviews and 372 papers were selected, clustered according to a common focus, and thoroughly reviewed. The PRISMA guideline was followed, the PICO model was adopted, and ROBINS-I and ROB 2.0 scoring were used to assess putative bias. Bias across studies regarding the LBR was also assessed using visual inspection of funnel plots and the trim and fill method. Categorical data were combined with a pooled-OR. The random-effect model was used to conduct the meta-analysis. Between-study heterogeneity was addressed using I2. Whenever not suitable for the meta-analysis, the included studies were simply described for their results. The study protocol was registered at http://www.crd.york.ac.uk/PROSPERO/ (registration number CRD42021275329). OUTCOMES: We included 372 original papers (335 retrospective studies, 30 prospective studies and 7 RCTs) and 41 reviews. However, most of the studies were retrospective, or characterized by small sample sizes, thus prone to bias, which reduces the quality of the evidence to low or very low. Reduced inner cell mass (7 studies, OR: 0.37, 95% CI: 0.27-0.52, I2 = 53%), or TE quality (9 studies, OR: 0.53, 95% CI: 0.43-0.67, I2 = 70%), overall blastocyst quality worse than Gardner's BB-grade (8 studies, OR: 0.40, 95% CI: 0.24-0.67, I2 = 83%), developmental delay (18 studies, OR: 0.56, 95% CI: 0.49-0.63, I2 = 47%), and (by qualitative analysis) some morphodynamic abnormalities pinpointed through time-lapse microscopy (abnormal cleavage patterns, spontaneous blastocyst collapse, longer time of morula formation I, time of blastulation (tB), and duration of blastulation) were all associated with poorer reproductive outcomes. Slightly lower LBR, even in the context of PGT-A, was reported among women ≥38 years (7 studies, OR: 0.87, 95% CI: 0.75-1.00, I2 = 31%), while obesity was associated with both lower LBR (2 studies, OR: 0.66, 95% CI: 0.55-0.79, I2 = 0%) and higher MR (2 studies, OR: 1.8, 95% CI: 1.08-2.99, I2 = 52%). The experience of previous repeated implantation failures (RIF) was also associated with lower LBR (3 studies, OR: 0.72, 95% CI: 0.55-0.93, I2 = 0%). By qualitative analysis, among hormonal assessments, only abnormal progesterone levels prior to transfer were associated with LBR and MR after PGT-A. Among the clinical protocols used, vitrified-warmed embryo transfer was more effective than fresh transfer (2 studies, OR: 1.56, 95% CI: 1.05-2.33, I2 = 23%) after PGT-A. Lastly, multiple vitrification-warming cycles (2 studies, OR: 0.41, 95% CI: 0.22-0.77, I2 = 50%) or (by qualitative analysis) a high number of cells biopsied may slightly reduce the LBR, while simultaneous zona-pellucida opening and TE biopsy allowed better results than the Day 3 hatching-based protocol (3 studies, OR: 1.41, 95% CI: 1.18-1.69, I2 = 0%). WIDER IMPLICATIONS: Embryo selection aims at shortening the time-to-pregnancy, while minimizing the reproductive risks. Knowing which features are associated with the reproductive competence of euploid blastocysts is therefore critical to define, implement, and validate safer and more efficient clinical workflows. Future research should be directed towards: (i) systematic investigations of the mechanisms involved in reproductive aging beyond de novo chromosomal abnormalities, and how lifestyle and nutrition may accelerate or exacerbate their consequences; (ii) improved evaluation of the uterine and blastocyst-endometrial dialogue, both of which represent black boxes themselves; (iii) standardization/automation of embryo assessment and IVF protocols; (iv) additional invasive or preferably non-invasive tools for embryo selection. Only by filling these gaps we may finally crack the riddle behind 'the black box of implantation'.

A review of the pathophysiology of recurrent implantation failure.

Implantation is a critical step in human reproduction. The success of this step is dependent on a competent blastocyst, receptive endometrium, and successful cross talk between the embryonic and maternal interfaces. Recurrent implantation failure is the lack of implantation after the transfer of several embryo transfers. As the success of in vitro fertilization has increased and failures have become more unacceptable for patients and providers, the literature on recurrent implantation failure has increased. While this clinical phenomenon is often encountered, there is not a universally agreed-on definition-something addressed in an earlier portion of this Views and Reviews. Implantation failure can result from several different factors. In this review, we discuss factors including the maternal immune system, genetics of the embryo and parents, anatomic factors, hematologic factors, reproductive tract microbiome, and endocrine milieu, which factors into embryo and endometrial synchrony. These potential causes are at various stages of research and not all have clear implications or immediately apparent treatment.

Effect of Methotrexate on Salpingostomy Completion Rate for Tubal Ectopic Pregnancy: A Retrospective Cohort Study.

STUDY OBJECTIVE: To determine whether completion rates of salpingostomy for tubal ectopic pregnancy are compromised by initial medical management with methotrexate (MTX). DESIGN: Retrospective cohort study. SETTING: Single academic hospital system. PATIENTS: Patients requiring surgery for ectopic pregnancy between 2006 and 2017. INTERVENTIONS: A subset of patients who went directly to surgery, and all patients who failed MTX before requiring surgery underwent detailed chart review. Salpingostomy plan and success rate and salpingostomy failure reasons were compared between patients pretreated with MTX and those who were MTX-untreated. MEASUREMENTS AND MAIN RESULTS: Among 94 ectopic pregnancies requiring surgery after failed MTX treatment, 55 (59%) underwent planned salpingostomy. From 693 ectopic pregnancies managed without MTX, 166 were analyzed in detail, of which 80 (48%) underwent planned salpingostomy. The patients who underwent planned salpingostomy were thinner (body mass index 27.3 ± 7.2 kg/m2 vs 29.3 ± 8.3 kg/m2; p = .048), less frequently African American (33% vs 47%; p = .017), and more likely to have a visualized adnexal lesion (70% vs 52%; p = .004) than those undergoing planned salpingectomy. Preoperative ultrasound identified fetal cardiac activity and hemoperitoneum at comparable rates. MTX exposure was not associated with age, body mass index, race, ectopic risk factors, human chorionic gonadotropin levels, or gestational age at diagnosis, but the patients treated with MTX underwent surgery later than those who were untreated (gestational age 53.4 ± 11.2 days vs 43.5 ± 11 days; p <.001). The differences between the adnexal lesion size and rates of fetal cardiac activity and hemoperitoneum on ultrasound related to MTX exposure did not meet significance. Planned salpingostomy was completed in 22 (40%) of the patients treated with MTX vs 34 (42%) of those who were untreated. The reasons for failure, surgery time, and rates of hemoperitoneum or ectopic rupture were not associated with MTX exposure. Body mass index, race, tubal anastomosis history, visualization of the adnexal lesion, and MTX exposure were not significantly associated with the salpingostomy rate in a multivariate logistic regression model, but having a subspecialist surgeon (odds ratio 2.70; 95% confidence interval, 1.08-6.76; p = .033) and tubal rupture at surgery (odds ratio 0.23; 95% confidence interval, 0.09-0.54; p = .001) were. CONCLUSION: The initial medical management of an ectopic pregnancy with MTX is not associated with a decreased salpingostomy success rate.

Considerations on the restriction of Assisted Reproductive Technology (ART) due to COVID-19.

The rapid rise of novel coronavirus disease 2019 (COVID-19) cases led the American Society for Reproductive Medicine (ASRM) to recommend immediate cessation of all new fertility treatment cycles on March 17, 2020. Controversial from the start, providers and patients expressed their opposition through online petitions, surveys, and other forums. While the impact of a delay in access to reproductive care is unknown, previous studies are reassuring that a delay in the timespan of months may not affect clinical outcomes. However, dropout from care during this pandemic remains a serious concern. Effective therapies against the virus and a vaccine are not on the immediate horizon. Accepting COVID-19 will likely be a part of our lives for the near future necessitates the modification of fertility protocols to keep patients, providers, and staff as safe as possible. We believe fertility treatment is an urgent, essential service that can be performed safely and responsibly during this pandemic.

Triple stimulation (TriStim) before bilateral oophorectomy in a young woman with ovarian cancer: a case report and review of the literature.

BACKGROUND: Double ovarian stimulation (DuoStim) involves two rounds of controlled ovarian stimulation (COS) and oocyte retrieval in immediate succession. It represents a promising approach to increase oocyte yield for patients with diminished ovarian reserve or those with limited time before fertility-threatening oncologic treatment. We report the case of a 31-year-old woman with Stage IC endometrioid ovarian cancer who underwent a triple stimulation or "TriStim," completing three rounds of COS and oocyte retrieval within 42 days prior to bilateral salpingo-oophorectomy. CASE PRESENTATION: A 31 year old nulligravid woman presented for fertility preservation counseling following a bilateral ovarian cystectomy that revealed Stage IC endometroid adenocarcinoma arising within endometrioid borderline tumors. The patient was counseled for bilateral salpingo-oophorectomy, lymph node dissection, and omentectomy followed by three cycles of carboplatin/paclitaxel. Prior to this, all within six weeks, the patient underwent three rounds of controlled ovarian stimulation using an antagonist protocol and human chorionic gonadotropin (hCG) trigger, resulting in vitrification of nine two-pronuclear zygotes (2PN), after which definitive surgery was performed. CONCLUSIONS: Advantages of DuoStim procedures are increasingly recognized, especially for oncology patients with limited time before potentially sterilizing cancer treatment. To our knowledge, this is the first report of a triple stimulation ("TriStim"). Our case highlights that triple stimulation is a viable option for patients needing urgent fertility preservation in order to maximize egg and embryo yield within a limited time period.