Endometrial disruption does not improve implantation in patients who have failed the transfer of euploid blastocysts

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'.

Office hysteroscopy before first in vitro fertilization. A randomized controlled trial

BACKGROUND

Implantation failure remains a mystery since decades. This procedure needs a "top quality embryo" and a "normal" uterine cavity. To assess uterine cavity before first in vitro fertilization (IVF), many diagnostic tools could be used. Hysteroscopy remains the gold standard to diagnose and treat intra-uterine anomalies. However, it is not clearly recommanded to offer an office hysteroscopy before first IVF when transvaginal ultrasound (TVUS) and hysterosalpingography (HSG) were normal.

PURPOSE

This study aimed to assess the role of office hysteroscopy before first IVF when no intra-uterine anomalies are suspected.

BASIC PROCEDURES

We conducted a randomized controlled trial including 171 women scheduled for their first IVF. Women were assigned to either Group I: office hysteroscopy before IVF or Group II: immediate IVF. We included women aged less than 40 years, having regular cycles, FSH levels less than10UI/l, antral follicular count ≥12, normal TVUS and HSG. Their body mass index (BMI) ranged from 19 to 30 kg/m². We excluded patients known having severe endometriosis, polycystic ovarian syndrome (PCOS) and oocyte receivers. The primary outcome were livebirth rate and clinical pregnancy rate.

MAIN FUNDINGS

Between january 2016 and september 2017, we randomly assigned 171 women to either Group I (n = 84) or Group II (n = 87). Hysteroscopy was done in the mid-follicular phase immediately before IVF. Baseline characteristics and IVF features were comparable between groups except for the IVF protocol. Live birth rate was 23,9% in Group I versus 19,3% in Group II. (p = 0,607). Clinical Pregnancy rate was 32,4% in Group I versus 21,7% in Group II. (p = 0,326). No statistical significance was observed for neither miscarriage rate nor multiple pregnancy rate. Hysteroscopy showed 30% unsuspected intra-uterine anomalies: 11 intra-uterine adhesions, 7 polyps, 7 clinical endometritis and one fibroid print. Therapeutic hysteroscopy was done only for 6 intra-uterine adhesions and 3 polyps. Other anomalies did not require operative hysteroscopy. Visual analog score during hysteroscopy was 4,69 +/-2,892. 5 women (6%) of Group I experienced discomfort during diagnostic hysteroscopy. Only one patient had vagal syncope. No further complications were observed.

PRINCIPAL CONCLUSIONS

Office hysteroscopy before first IVF seems not improve IVF results. Minimal intra-uterine anomalies not diagnosed by transvaginal ultrasound and hysterosalpingography do not seem to reduce IVF results.

Effect of endometrial injury during menstruation on clinical outcomes in frozen-thawed embryo transfer cycles: A randomized control trial

Aim

To explore the clinical effect of endometrial injury (EI) on the third day of the menstrual cycle before frozen–thawed embryo transfer (frozen–thawed ET) on patients experienced two or more implantation failures.

Methods

A total of 200 patients who suffered at least two failed hormone‐replacement therapies and frozen–thawed ET were randomly divided into two groups: EI group and control group (n = 100 in each group). Patients in the EI group received local EI with a Pipelle catheter on the third day of the menstrual cycle before frozen–thawed ET. Primary outcomes were live birth, clinical pregnancy and implantation rates. Secondary outcomes were biochemical, multiple and ectopic pregnancy rates and abortion rates.

Results

The rate of live birth in EI group (51.00%) was significantly higher than that of control group (36.00%) (P = 0.032). Clinical pregnancy and implantation rates in EI group were significantly higher comparing to control group (64.00% vs 48.00%, P = 0.023 and 46.74% vs 30.11%, P = 0.001). The rate of multiple pregnancy in EI group (37.50%) was significantly higher than that of control group (18.75%) (P = 0.031). No significant difference in ectopic pregnancy rate and abortion rate was observed between EI group and control group.

Conclusion

Applying EI to patients experienced two or more implantation failures on the third day of the menstrual cycle before frozen–thawed ET can improve clinical outcomes.

Scratching and IVF: any role?

PURPOSE OF REVIEW

To review updated information on the influence of endometrial scratching on IVF.

RECENT FINDINGS

Endometrial receptivity remains an important rate-limiting step affecting the success of IVF. The current evidence on the effect of endometrial scratching on IVF ranges from marked improvement, no difference to a potentially negative impact. The heterogeneity of studies presents a challenge in interpretation of data for routine clinical practice.

SUMMARY

Endometrial scratching performed in the preceding cycle is associated with improved clinical pregnancy and live birth rates in women with recurrent implantation failure, but not in unselected subfertile women undergoing IVF. Most of the current literature are underpowered and at high risk of bias.

Fertile ground: human endometrial programming and lessons in health and disease

The human endometrium is a highly dynamic tissue that is cyclically shed, repaired, regenerated and remodelled, primarily under the orchestration of oestrogen and progesterone, in preparation for embryo implantation. Humans are among the very few species that menstruate and that, consequently, are equipped with unique cellular and molecular mechanisms controlling these cyclic processes. Many reproductive pathologies are specific to menstruating species, and studies in animal models rarely translate to humans. Abnormal remodelling and regeneration of the human endometrium leads to a range of reproductive complications. Furthermore, the processes regulating endometrial remodelling and implantation, including those controlling hormonal impact, breakdown and repair, stem/progenitor cell activation, inflammation and cell invasion have broad applications to other fields. This Review presents current knowledge regarding the normal and abnormal function of the human endometrium. The development of biomarkers for prediction of uterine diseases and pregnancy disorders and future avenues of investigation to improve fertility and enhance endometrial function are also discussed.

Clinical background affecting pregnancy outcome following local endometrial injury in infertile patients with repeated implantation failure

Local endometrial injury (LEI) has been performed as a promising medical intervention to improve the pregnancy outcome in infertile women suffering from repeated implantation failure (RIF) in in vitro fertilization-embryo transfer cycles. The effect of LEI, however, remains controversial. The aim of this retrospective study was to identify the subgroups of patients with RIF who benefit from LEI. We compared the clinical parameters between the patients who had had a clinical pregnancy in the subsequent embryo transfer cycle following the LEI cycle (LEI-CP group, n = 94) and those who had resulted in negative pregnancy test (LEI-NP group, n = 114). The female age, basal follicle stimulating hormone concentration, number of past oocyte pickup cycles, and embryos/blastocysts transferred in the past three RIF cycles were significantly (p < 0.047) lower in the LEI-CP group than the LEI-NP group. The prevalence of polycystic ovarian syndrome was significantly (p = 0.0059) higher in the LEI-CP group than in the LEI-NP group. These findings suggest that LEI is most effective to improve the pregnancy outcome in patients undergoing RIF with uncompromised ovarian reserve, particularly in those with polycystic ovarian syndrome.

The endometrial preparation for frozen-thawed euploid blastocyst transfer: a prospective randomized trial comparing clinical results from natural modified cycle and exogenous hormone stimulation with GnRH agonist

PURPOSE

The aim of the study was to evaluate two methods of endometrial preparation for frozen-thawed single euploid blastocyst transfer: modified natural and artificial cycle with GnRH-agonist pituitary suppression.

METHODS

In this prospective, controlled randomized trial, a total of 236 patients undergoing infertility treatment were randomized in 1:1 ratio; 118 received a frozen-thawed single euploid blastocyst transfer in a modified natural cycle and 118 in an artificial cycle with GnRH-agonist pituitary suppression. In the artificial protocol, GnRH-agonist combined with estradiol valerate was administered. In the natural protocol, only final oocyte maturation was induced using human chorionic gonadotropin administration. The primary end-points were the clinical pregnancy and implantation rates; the secondary end-points were the cost-benefit in terms of drug cost and the number of visits and the woman psychological distress caused by the treatment.

RESULTS

No significant differences were found in clinical pregnancy, implantation, and miscarriage rates between protocols. The number of clinical and ultrasound controls and the number of laboratory dosages and venous samplings were similar in both study groups. No significant differences were found between the groups in the anxiety and depression values before the start of treatment, on the days of progesterone administration, the blastocyst transfer, and pregnancy test.

CONCLUSIONS

The findings of this study evidence that in case of frozen-thawed single euploid blastocyst transfer, both protocols are equally effective in terms of clinical outcomes, cost-benefit, and patient compliance. The choice of endometrial preparation protocol should be based on women menstrual and ovulatory characteristics or otherwise on patient need for cycle planning.

TRIAL REGISTRATION

www.clinicaltrials.gov with number NCT02378584.

Comparison of Uterine Receptivity between Fertile and Unexplained Infertile Women by Assessment of Endometrial and Subendometrial Perfusion Using Contrast-Enhanced Ultrasound: Which Index is Better--Peak Intensity or Area under the Curve?

The goal of this study was to compare uterine receptivity between women with normal fertility and those with unexplained infertility during natural cycles by assessment of endometrial and subendometrial perfusion using contrast-enhanced ultrasound (CEUS). We wanted to determine the better index: peak intensity (PI) or area under the curve (AUC). Thirty women with unexplained infertility were recruited into the study group, and 30 women with normal fertility were recruited into the control group. All women underwent CEUS during the late proliferative phase, ovulation phase, and implantation window of a menstrual cycle. Endometrial PI, endometrial AUC, subendometrial PI and subendometrial AUC were analyzed. In the late proliferative phase, the control group had a significantly higher endometrial PI (p < 0.001) as well as subendometrial PI (p < 0.001) and AUC (p = 0.004) than the study group. In the ovulation phase, the control group had a significantly higher endometrial PI (p < 0.001) and AUC (p = 0.021), as well as subendometrial PI (p < 0.001) and AUC (p = 0.003). During the implantation window, there were no significant differences between the two groups. Only subendometrial PI underwent a significant periodic change during the menstrual cycle in both groups. This finding was further confirmed by evaluation of the microvessel density of endometria. In conclusion, CEUS can be used to assess endometrial and subendometrial perfusion to evaluate uterine receptivity. Subendometrial PI was the most sensitive index compared with endometrial PI, endometrial AUC and subendometrial AUC.