The effect of endometrial injury on implantation and clinical pregnancy rates

Outcome of Different Endometrial Preparation Protocols Prior to Frozen-Thawed Embryo Transfer on Pregnancy Outcomes in Women with Repeated Implantation Failure

Aim

To compare the pregnancy outcomes of frozen-thawed embryo transfer (FET) cycles among women with repeated implantation failure (RIF) treated with various endometrial preparation protocols.

Methods

A total of 605 women with RIF were retrospectively recruited between January 2017 and December 2020 from Northern Theater General Hospital. Patients were divided into natural cycles, hormone replacement therapy (HRT) cycles, depot gonadotropin-releasing hormone (GnRH) agonist-HRT, and endometrial scratching (ES) plus depot GnRH agonist-HRT. The primary endpoint was clinical pregnancy rate, while secondary endpoints included live birth rate and pain assessment.

Results

Of the 605 recruited patients, 63 were undergoing natural cycles, 281 were treated with HRT cycles, 141 treated with depot GnRH agonist-HRT, and 120 treated with ES combined with depot GnRH agonist-HRT. There were significant differences among protocols on clinical pregnancy rate (P=0.029), while no significant difference was observed among protocols on live birth rates (P=0.108). Multivariate analyses suggested that HRT (odds ratio [OR]: 0.50; 95% confidence interval [CI]: 0.28-0.89; P=0.019) and depot GnRH agonist-HRT (OR: 0.49; 95% CI: 0.27-0.91; P=0.021) cycles were associated with a lower clinical pregnancy rate as compared with natural cycles, while no significant difference between ES combined with depot GnRH agonist-HRT and natural cycles for clinical pregnancy rates (OR: 0.72; 95% CI: 0.38-1.36; P=0.313). Moreover, the HRT (OR: 0.70; 95% CI: 0.39-1.28; P=0.239), depot GnRH agonist-HRT (OR: 0.67; 95% CI: 0.35-1.29; P=0.229), and ES combined with depot GnRH agonist-HRT (OR: 1.11; 95% CI: 0.58-2.14; P=0.754) cycles had no significant effects on live birth rate as compared with natural cycles. A total of 87.50% patients treated with ES combined with depot GnRH agonist-HRT reported pain during the procedure.

Conclusion

ES and depot GnRH agonists could be considered for RIF women with high-quality blastocysts, 14 days after verified transplantation failure.

The impact of endometrial scratch performed in mid-luteal phase on the endometrium whole genome transcriptomic profiles in following menstrual cycle

The value of endometrial scratch in women with recurrent embryo transfer has been controversial. Endometrial scratch is often performed in the mid-luteal phase of the cycle preceding embryo transfer but there is little scientific evidence if it affects the whole genome transcriptomic profile of peri-implantation endometrium in the following cycle. A prospective longitudinal cohort study was conducted in a university assisted reproductive unit. A total of eight women with recurrent implantation failure (RIF) were included. Each participant had endometrial biopsy twice, first biopsy on day LH + 7 in natural cycle and second on day LH + 7 of the following cycle. R package was used to identify differentially expressed genes between the sample and enriched gene ontology. However, the paired sample showed no significant difference, neither known endometrial receptive gene set nor other genes, before and after the endometrial scratch. It suggests that endometrial scratch performed during previous mid-luteal phase did not affect the transcriptomic profiles of endometrium on day LH + 7 in women with RIF.

Immune Cell Functionality during Decidualization and Potential Clinical Application

Due to a vast influx in the secretory phase of the menstrual cycle, leukocytes represent 40-50% of the decidua at the time of implantation. Their importance for the implantation, maintenance of pregnancy, and parturition are known yet not fully understood. Thus, in idiopathic infertility, decidual immune-related factors are speculated to be the cause. In this review, the immune cell functions in the decidua were summarized, and clinical diagnostics, as well as interventions, were discussed. There is a rising number of commercially available diagnostic tools. However, the intervention options are still limited and/or poorly studied. In order for us to make big steps towards the proper use of reproductive immunology findings, we need to understand the mechanisms and especially support translational research.

Impact of endometrial scratching on reproductive outcome in patients: A systematic review and meta-analysis

BACKGROUND

Endometrial scratching (ES) has demonstrated initial success in women with recurrent implantation failure, but the effect in women with 1 previous assisted reproductive technology (ART) failure is unknown. This meta-analysis aimed to evaluate the impact of ES as a treatment in clinical outcomes for women with at least 1 failed in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI)/Intrauterine Insemination (IUI).

METHODS

PubMed, Medline, Embase, Cochrane Library, Web of Science, CNKI, and EMCC databases were searched for randomized controlled trial studies utilizing endometrial scratching for infertility women with at least 1 failed assisted reproductive technology (ART) to collect pregnancy outcomes, including clinical pregnancy rate (CPR), embryo implantation rate (IR), miscarriage rate (MR), live birth rate (LBR), and multiple pregnancy rate (MPR).

RESULTS

Sixteen randomized controlled trial (RCT) studies were included in this meta-analysis, including 1770 women in the intervention group and 1934 women in the control group. Overall, the CPR, IR and LBR were significantly higher in the intervention group than in the control group (for CPR, n = 1430, 16 studies, P = .0002, risk ratio (RR) = 1.59, 95% confidence interval [CI] [1.24, 2.03]; for IR, n = 859, 10 studies, P = .0003, RR = 1.67, 95% CI [1.26, 2.21]; for LBR, n = 156, 6 studies, P = .0005, RR = 1.59, 95% CI [1.22, 2.06]). Nonetheless, there was no significant difference in MR (n = 344, 11 studies, P = .62, risk ratio (RR) = 0.92, 95% confidence interval [CI] [0.66, 1.29]) and MPR (n = 98, 3 studies, P = .39, risk ratio (RR) = 0.81, 95% confidence interval [CI] [0.51, 1.30]) between the intervention group and the control group.

CONCLUSION

Endometrial scratching is considered to enhance the reproductive outcomes of embryo implantation. Additional randomized controlled studies are recommended to identify the appropriate time of invasion and the applicable population to confirm whether it can become a routine operation.

Comparing the effects of endometrial injury in the luteal phase and follicular phase on in vitro fertilization treatment outcomes

BACKGROUND

Several studies have shown that endometrial injury improves clinical pregnancy outcomes in patients undergoing in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) treatment with a history of implantation failure. However, endometrial injury can be performed in the follicular phase (FP) followed by embryo transfer in the same menstrual cycle or in the luteal phase (LP) before the embryo transfer cycle.

METHOD

This prospective cohort study was conducted from January 2015 to September 2021, and a total of 487 patients were included. All included patients had a history of a failed implantation cycle. They were divided into two groups: the FP group (N = 330), in which endometrial injury was performed on menstrual day 3-5, and the LP group (N = 157), in which endometrial injury was performed in the cycle preceding embryo transfer 7 days after ovulation.

RESULTS

First, in unselected patients, the implantation rate and clinical pregnancy rate were comparable between the LP and FP groups. However, in patients with a history of ≥ 2 failed transfer cycles, the implantation rate was significantly higher in the LP group than in FP group (43.09% versus 33.33%, P = 0.03). Moreover, the clinical pregnancy rate was also significantly higher in patients in the LP group than in patients in the FP group (60.17% versus 46.15%, P=0.02). In addition, logistic regression analysis showed that endometrial injury in the LP group was an independent factor affecting clinical pregnancy outcome in patients with a history of ≥ 2 failed transfer cycles (aOR = 2.05, 90% CI:1.22-3.47, P=0.01).

CONCLUSION

Endometrial injury improves pregnancy outcomes when performed in the luteal phase compared with the follicular phase in patients with a history of ≥ 2 failed transfer cycles but not in unselected patients.

The Addition of Endometrial Injury to Freeze-All Strategy in Women with Repeated Implantation Failures

(1) Background: Recurrent implantation failure (RIF) after IVF remains a challenging topic for fertility specialists and a frustrating reality for patients with infertility. Various approaches have been investigated and applied towards the improvement of clinical outcomes. Through a nonrandomized clinical trial, we evaluated the effect of the combination of hysteroscopic endometrial injury and the freeze-all technique on pregnancy parameters in a cohort of RIF patients; (2) Methods: The study group comprised of 30 patients with RIF that underwent a hysteroscopic endometrial injury prior to a frozen embryo transfer cycle; another 30 patients with RIF, comprising the control group, underwent a standard frozen cycle with no adjuvant treatment before. Live birth comprised the primary outcome. Logistic and Poisson regression analyses were implemented to reveal potential independent predictors for all outcomes. (3) Results: Live birth rates were similar between groups (8/30 vs. 3/30, p = 0.0876). Biochemical and clinical pregnancy and miscarriages were also independent of the procedure (p = 0.7812, p = 0.3436 and p = 0.1213, respectively). The only confounding factor that contributed to biochemical pregnancy was the number of retrieved oocytes (0.1618 ± 0.0819, p = 0.0481); (4) Conclusions: The addition of endometrial injury to the freeze-all strategy in infertile women with RIF does not significantly improve pregnancy rates, including live birth. A properly conducted RCT with adequate sample size could give a robust answer.

Improving reproductive outcomes of intrauterine insemination: Does endometrial scratch injury help? A randomised controlled trial

OBJECTIVE(S)

Current evidence suggests that endometrial injury improves clinical pregnancy rate while having no effect on miscarriages in women undergoing IVF/ICSI. However, there is no substantial evidence to advocate the use of endometrial injury to benefit the outcomes of IUI treatment. Additionally, there is no clear consensus about the ideal timing, underlying mechanism and optimum intensity of endometrial injury required. The study examines the effect of intentional endometrial injury/scratch in the early proliferative phase of stimulated cycle on reproductive outcomes (clinical and ongoing pregnancy rates and miscarriage occurrence) of intra-uterine insemination treatment (IUI).

STUDY DESIGN, SIZE, DURATION

This prospective, randomized control interventional study was conducted in a tertiary level teaching institution from April 2018 to February 2020. 150 eligible couples requiring IUI treatment who agreed to participate were randomly allocated on 1:1 basis to either control or intervention group. The trial participants received up to 3 cycles ovulation induction with clomiphene citrate and intra-uterine insemination. In addition, women in intervention group were subjected to endometrial scratch injury on day 6-7 of their stimulated cycle. 154 cycles in control arm and 128 cycles in intervention group were analyzed for clinical pregnancy, miscarriages and pain experienced by the women during endometrial scratch injury using the statistical package SPSS (version 21).

RESULT

Similar cumulative clinical pregnancy rates (12.5% Vs 13.6%, RR 1.21, 95% CI 0.44-3.37, p = 0.713), biochemical pregnancy rates (17.1% vs 22.9%, RR 1.43, CI 0.59-3.47, p = 0.421) and ongoing pregnancy rates (10.93% Vs 11.47%, RR 1.05, CI 0.35-3.21, p = 924) were observed in control and intervention arms. Likewise, the relative risk of miscarriage occurrence in the intervention arm was 1.32 (95% CI 0.39-4.32, p = 1.000) which was not statistically different from control group. Mean pain score of 6.93 on numerical pain rating scale was experienced by women whilst having endometrial scratch injury.

CONCLUSIONS

There is insufficient evidence to defend the use of endometrial scratch injury in intra-uterine insemination treatment, as it is moderately painful and have uncertain beneficial influence on reproductive outcomes.

Endometrial scratch injury with office hysteroscopy before IVF/ICSI: A randomised controlled trial

OBJECTIVE

Endometrial scratch injury (ESI) has been proposed to improve endometrial receptivity and thereby increase implantation rates in assisted reproductive technology (ART) treatment. ESI has been widely incorporated into clinical practice despite inconclusive evidence of its effect on reproductive outcomes. We aimed to assess pregnancy and live birth rates in subfertile women receiving ESI before IVF treatment in comparison to controls.

STUDY DESIGN

This was a randomised controlled trial (RCT) with no blinding of participants, investigators or health care personnel. Women in ART treatment were allocated to either office hysteroscopy with ESI (ESI group) or no intervention (control group). In total 184 women in IVF/ICSI treatment with minimum one previous failed IVF/ICSI cycle, were included in the final analysis. The primary outcome was positive serum hCG (s-hCG). Secondary outcomes were ongoing pregnancy and live birth rate. Only per-protocol analyses were performed as all patients included at one centre had to be excluded. The trial is registered at ClinicalTrials.gov, NCT01743391.

RESULTS

Our results showed a non-significant increase in positive s-hCG (OR 1.23, 95 % CI (0.65-2.33)), ongoing pregnancy (OR 1.52, 95 % CI (0.73-3.17)), and live birth rates (OR 1.69, 95 % CI (0.78-3.64)) per randomised woman between the ESI and the control group.

CONCLUSION

We observed no significant differences in positive s-hCG or other reproductive outcomes in the ESI vs. the control group. While the crude estimates of positive reproductive outcomes were higher in the ESI group, statistical significance was not reached, and the study was not powered to show smaller differences. However, data from this study will be re-evaluated in the context of an individual participant data meta-analysis (IPD-MA) of RCTs on ESI.

Endometrial "Scratching" An update and overview of current research

About one in every six couples is affected by sterility. Assisted reproduction procedures are currently the treatment of choice for a number of patients who desire children. Many causes of sterility can be overcome with the aid of in vitro fertilization, but successful implantation of the embryos is the major limiting factor. Failure of implantation may occur repetitively. In the treatment of sterility, many approaches have been used to overcome the barrier of implantation failure and improve the chances of successful nidation. Scratching the endometrium prior to embryo transfer has been suggested as one means of enhancing the likelihood of implantation. The current literature was examined to investigate if there was any possible benefit from endometrial scratching. The studies were divided according to whether the women suffered from recurrent implantation failure or not. In summary, it was found that unselected subfertile women generally benefit less from endometrial scratching, but scratching appears to be successful in women who have experienced repeated implantation failure. Although the heterogeneous body of data on the subject deserves further clarification. The latest data presented at “European Society of Human Reproduction and Embryology” 2018 in Barcelona suggested that the method should be abandoned.

The impact of intentional endometrial injury on reproductive outcomes: a systematic review and meta-analysis

BACKGROUND

Endometrial injury is an intentional damage made to the endometrium, usually produced by a Pipelle catheter. Over the last two decades, endometrial injury has been studied to improve implantation rates and decrease the incidence of implantation failure in invitro fertilization (IVF) cycles. Recently, additional studies of endometrial injury, performed not only in patients with implantation failure but also in intrauterine insemination cycles, have been conducted, and the endometrial injury made by hysteroscopy has been researched. The evidence describing the impact of endometrial injury is controversial; therefore, we conducted a systematic review and meta-analysis to examine the issue.

OBJECTIVE AND RATIONALE

Our objective is to review the research that has been done until now and perform a meta-analysis regarding endometrial injury and its influence on implantation success and pregnancy rates in patients with at least one failed IVF cycle. In particular, we aim to study the efficacy of the procedure and look for confounding factors, such as maternal age, in assessing the efficacy of endometrial injury.

SEARCH METHODS

The systematic review of the literature was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement. Study protocol can be assessed at PROSPERO International prospective register of systematic reviews (registration number CRD42018092773). Searches were conducted by an experienced research librarian in the following databases: MEDLINE(R) using the OvidSP interface and PUBMED, Embase, Web of Science and Cochrane Library. This review considered for inclusion randomized-controlled trials examining the success of performing local endometrial injury on IVF outcomes in women with previous failed IVF cycles.

OUTCOMES

Ten studies, comprising a total of 1260 patients, were selected. Overall, when studying the effect of endometrial injury on clinical pregnancy rates (CPRs) and live birth rates (LBRs), higher rates were shown in the endometrial injury group. However, endometrial injury did not significantly improve CPRs and LBRs, when considering sub-group analyses of studies including patients with two or more failed IVF cycles, studies examining older patients or studies which did not include hysteroscopy. There was no significant difference found regarding multiple pregnancy rates, while a handful of studies showed an improvement in miscarriage rates.

WIDER IMPLICATIONS

Endometrial injury should be used restrictively and not routinely in clinics. Maternal age and number of previous failed treatment cycles may be contributing factors which can influence the results when studying the effect of endometrial local injury. It is possible that the relative contribution of endometrial receptivity to the chances of implantation decreases with any additional failed cycle. The optimal study to prove the efficacy of local endometrial injury on implantation and pregnancy rates, should be a random-controlled trial studying the effect of local endometrial injury in oocyte donation cycles, in recipients with repeated implantation failure. This kind of study will conclude whether local endometrial injury is an efficient procedure with minimum confounding factors, and may assist in defining the population, even outside of donation cycles, that will benefit from the procedure.

Recurrent implantation failure: which patients benefit from endometrial scratching prior to IVF?

PURPOSE

Endometrial scratching (ES) using a biopsy catheter prior to the IVF cycle in the repeated implantation failure (RIF) population has been suggested, but no convincing evidence of its benefit has been presented until now.

METHODS

A retrospective mono-center study among 300 consecutive IVF-RIF cycles following evaluation of the ovarian reserve, hysterosalpingography or hysteroscopy, pelvic ultrasound, thrombophilia evaluation, karyotyping and assessment of male sperm parametrs. The findings within normal limits. All the patients offered ES, 78 consented and underwent ES prior to their next IVF cycle.

RESULTS

A comparison of treatment outcomes between the post-ES cycles (n = 78) and the non-ES cycles (222) demonstrated the following: 34 (43.5%) versus 14 (6.3%) conceptions, respectively (p = 0.001) and 30 (38.4%) versus 2 (0.9%) clinical pregnancies, respectively (p < 0.001%), emphasizing an extremely high biochemical pregnancy rate among the non-ES cycles. Implantation rate was 19.7% versus 0.4%, respectively (p < 0.001) and live birth rate was 33.33% (26 newborns) versus 0.45% (1 newborn), respectively (p < 0.001). Since there were more embryos available for transfer and more top-quality embryos in the post-ES-IVF conception cycles, the role of ES became questionable. A multivariate analysis that included ES and the percentage of top-quality embryos demonstrated that ES was an independent factor highly correlated with conception in this particular RIF population.

CONCLUSIONS

ES proved to be an efficient tool in a particular subgroup of RIF patients with fertility investigation results within normal limits, an optimal ovarian response to gonadotropins, and a high percentage of top-quality embryos. Nevertheless, the results should not be overestimated, since the study has limitations related to its retrospective model.

Implantation failure of endometrial origin: what is new?

PURPOSE OF REVIEW

To review recent findings related to possible causes of recurrent implantation failure of endometrial origin in normal uterus.

RECENT FINDINGS

Recent evidences suggest that in apparently normal endometria, RIF may associate with molecular and functional changes in the uterus such as abnormal endometrial microbiota, including the presence of chronic endometritis, poor synchronization between the blastocyst and endometrium, and/or excessive uterine peristalsis. An altered endometrial microbiota detected by molecular techniques has been recently related to poorer embryo implantation, even in apparently normal endometria. The use of the endometrial receptivity analysis test to obtain an objective signature of endometrial receptivity has shown to improve the reproductive performance in RIF patients. The diagnosis of uterine peristalsis, however, remains challenging since the usual evaluation by transvaginal ultrasound is not accurate, and drugs tested to reduce uterine peristalsis and enhance embryo implantation have not been clearly beneficial. Finally, endometrial injury to improve implantation rates remains controversial being definitive well-designed trials needed to assess its benefit, if any.

SUMMARY

In recurrent implantation failure of endometrial origin an altered pattern of the microbial endometrial ecosystem, a displaced window of implantation leading to desynchronization between the blastocyst and the endometrium, or an altered pattern of uterine contractions during embryo transfer may be factors to consider in our attempt to solve this clinical issue. New diagnostics for assessing these conditions and new therapies to improve these dysfunctional situations are currently under investigation to be presumably included in the near future in the work-up of affected patients.

Single and double endometrial scratching (ES) in infertile women with strict criteria of recurrent implantation failure (RIF)

Controversies surrounding the effect of ES on pregnancy outcome in women with RIF are mostly due to the poorly defined target population. We evaluated the effect of ES on clinical outcomes in women with strict criteria of RIF before IVF/ICSI. We also examined the effect of ES on the expression of markers of endometrial receptivity. Women with failed implantation after transfer of seven or more top quality day 3 embryos or three blastocysts underwent the scratch procedure on exact days of the cycle prior to IVF/ICSI. Results were compared to no scratch control group. Using histopathology, immunohistochemistry, and scanning electron microscopy, we also examined the effect of injury on the endometrial receptivity in a separate series of observations with double ES. Cumulative pregnancy rate was significantly higher in the study group as compared to control (54.8% vs. 29.0%; p < .05). The effect of ES on the clinical outcome was seen during fresh ET, but not on the next FET cycles. ES improves impaired endometrial receptivity by partially normalizing the expression of estrogen and progesterone receptors (ERs, PRs) and pinopodes. We concluded that in a well-defined subpopulation of infertile women with RIF, ES significantly enhances pregnancy rates. ES has a specific impact on endometrial receptivity normalizing the expression of some markers.

Effect of local endometrial injury in proliferative vs. luteal phase on IVF outcomes in unselected subfertile women undergoing in vitro fertilization

BACKGROUND

Mechanical endometrial injury prior to IVF has been suggested as a means to increase implantation rates by improving endometrial receptivity. However, the effects of endometrial injury in proliferative vs. luteal phase have not been studied before. This study aimed to explore whether endometrial injury in the proliferative phase of the preceding cycle before in vitro fertilization/embryo transfer (IVF-ET) improves the clinical outcomes in unselected subfertile women compared with injury in luteal phase.

METHODS

A group of 142 patients who were good responders to hormonal stimulation were randomized into four groups: injury group (group A: endometrial injury in proliferative phase, n = 38; group B: endometrium injury in luteal phase, n = 32), and non-injury group as control (group C: non-injury in proliferative phase, n = 36; group D: non-injury in luteal phase, n = 36). Patients in injury groups underwent endometrial injury in either proliferative phase or luteal phase in the preceding cycle before IVF treatment. Clinical outcomes including implantation, pregnancy, and live birth rates were analyzed among the four groups.

RESULTS

The baseline characteristics of the four groups including age, body mass index, duration, type and causes of infertility were similar. There were no significant differences in implantation, clinical pregnancy or live birth rates between injury group and non-injury group. Moreover, there were also no significant differences in implantation, clinical pregnancy, or live birth rates in injury in proliferative phase compared with luteal phase.

CONCLUSIONS

Endometrial injury in the cycle preceding IVF of unselected subfertile women does not increase implantation, clinical pregnancy, or live birth rates. Furthermore, there is no significant difference in clinical outcomes between endometrial injury in the proliferative phase and injury in the luteal phase.

TRIAL REGISTRATION

This study was retrospectively registered on May 26th, 2017 (ChiCTR-IOR-17011506).