Potential Pathophysiological Mechanisms of the Beneficial Role of Endometrial Injury in In Vitro Fertilization Outcome

Enhancing uterine receptivity for embryo implantation through controlled collagenase intervention

Ineffective endometrial matrix remodeling, a key factor in infertility, impedes embryo implantation in the uterine wall. Our study reveals the cellular and molecular impact of human collagenase-1 administration in mouse uteri, demonstrating enhanced embryo implantation rates. Collagenase-1 promotes remodeling of the endometrial ECM, degrading collagen fibers and proteoglycans. This process releases matrix-bound bioactive factors (e.g., VEGF, decorin), facilitating vascular permeability and angiogenesis. Collagenase-1 elevates embryo implantation regulators, including NK cell infiltration and the key cytokine LIF. Remarkably, uterine tissue maintains structural integrity despite reduced endometrial collagen fiber tension. In-utero collagenase-1 application rescues implantation in heat stress and embryo transfer models, known for low implantation rates. Importantly, ex vivo exposure of human uterine tissue to collagenase-1 induces collagen de-tensioning and VEGF release, mirroring remodeling observed in mice. Our research highlights the potential of collagenases to induce and orchestrate cellular and molecular processes enhancing uterine receptivity for effective embryo implantation. This innovative approach underscores ECM remodeling mechanisms critical for embryo implantation.

Autologous platelet-rich plasma for assisted reproduction

BACKGROUND

Autologous platelet-rich plasma (PRP) consists of plasma and a concentrate of platelets extracted from fresh whole blood of the person being treated. Research has suggested that intrauterine or intraovarian infusion/injection of PRP before embryo transfer may improve endometrial receptivity and response to ovarian stimulation in women undergoing assisted reproduction. We compared these interventions to standard treatment, placebo, or other interventions (mechanical or pharmacological).

OBJECTIVES

To assess the effectiveness and safety of intrauterine and intraovarian infusion/injection of platelet-rich plasma in infertile women undergoing assisted reproductive technology cycles.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility Group's Specialised Register, CENTRAL, MEDLINE, Embase, and the Epistemonikos database in January 2023. We also searched the reference lists of relevant articles and contacted the trial authors and experts in the field for any additional trials.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that evaluated the application of PRP in the uterine cavity, ovaries, or both versus no intervention, placebo, or any other intervention (either mechanical or pharmacological) in women undergoing in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) cycles.

DATA COLLECTION AND ANALYSIS

We followed standard methodological procedures recommended by Cochrane, including use of the updated risk of bias tool (RoB 2). The primary outcomes were live birth (or ongoing pregnancy) and miscarriage. The secondary outcomes were clinical pregnancy, complications of the procedure, multiple pregnancy, ectopic pregnancy, fetal growth restriction, preterm delivery, and fetal abnormality. We estimated the average effect of the interventions by fitting a Der Simonian-Laird's random-effects meta-analysis model. We reported pooled odds ratios (ORs) with 95% confidence intervals (CIs). We restricted the primary analyses to trials at low risk of bias for the outcomes and performed sensitivity analyses that included all studies.

MAIN RESULTS

We included 12 parallel-group RCTs that recruited a total of 1069 women. We identified three different comparison groups. Using GRADE, we assessed the certainty of evidence as very low for almost all outcomes. Intrauterine injection/infusion of platelet-rich plasma versus no intervention or placebo Nine studies evaluated intrauterine PRP versus no intervention or placebo. Eight included women with at least two or three previous implantation failures. Only one was assessed at low risk of bias for each outcome. This study provided very low-certainty evidence about the effect of intrauterine PRP injection versus no intervention on live birth (OR 1.10, 95% CI 0.38 to 3.14; 94 women) and miscarriage (OR 0.96, 95% CI 0.13 to 7.09; 94 women). If the likelihood of live birth following no intervention is assumed to be 17%, then the likelihood following intrauterine PRP would be 7% to 40%; and if the risk of miscarriage following no intervention is 4%, then the risk following intrauterine PRP would be 1% to 24%. When we analyzed all studies (regardless of risk of bias), we found very low-certainty evidence about the effect of intrauterine PRP compared with placebo or no intervention on live birth or ongoing pregnancy (OR 2.38, 95% CI 1.16 to 4.86; I² = 54%; 6 studies, 564 women) and miscarriage (OR 1.54, 95% CI 0.59 to 4.01; I² = 0%; 5 studies, 504 women). The study at low risk of bias provided very low-certainty evidence about the effect of intrauterine PRP compared with no intervention on clinical pregnancy (OR 1.55, 95% CI 0.64 to 3.76; 94 women) and ectopic pregnancy (OR 2.94, 95% CI 0.12 to 73.95; 94 women). The synthesis of all studies provided very low-certainty evidence about the effect of intrauterine PRP compared with placebo or no intervention on clinical pregnancy (OR 2.22, 95% CI 1.50 to 3.27; I² = 24%; 9 studies, 824 women), multiple pregnancy (OR 2.68, 95% CI 0.81 to 8.88; I² = 0%; 2 studies, 240 women), and ectopic pregnancy (OR 2.94, 95% CI 0.12 to 73.95; 1 study, 94 women; very low-certainty evidence). Intrauterine infusion of PRP may increase the risk of preterm delivery compared with no intervention (OR 8.02, 95% CI 1.72 to 37.33; 1 study, 120 women; low-certainty evidence). No studies reported pain, infection, allergic reaction, fetal growth restriction, or fetal abnormality. Intrauterine infusion of platelet-rich plasma versus intrauterine infusion of granulocyte colony-stimulating factor Two RCTs evaluated intrauterine PRP versus intrauterine granulocyte colony-stimulating factor (G-CSF); both included women with thin endometrium, and neither was judged at low risk of bias for any outcome. We are uncertain about the effect of intrauterine PRP compared with intrauterine G-CSF on live birth (OR 0.88, 95% CI 0.43 to 1.81; 1 study, 132 women; very low-certainty evidence), miscarriage (OR 1.94, 95% CI 0.63 to 5.96; 1 study, 132 women; very low-certainty evidence), and clinical pregnancy (OR 1.24, 95% CI 0.66 to 2.35; 2 studies, 172 women; very low-certainty evidence). Neither study reported adverse outcomes other than miscarriage. Intraovarian injection of platelet-rich plasma versus no intervention One RCT evaluated PRP injection into both ovaries versus no intervention; it was judged at high risk of bias for the two outcomes it reported. We are uncertain about the effect of intraovarian PRP injection compared with no intervention on ongoing pregnancy (OR 1.09, 95% CI 0.33 to 3.63; 73 women; very low-certainty evidence) and clinical pregnancy (OR 0.90, 95% CI 0.31 to 2.60; 73 women; very low-certainty evidence). The study examined no safety outcomes.

AUTHORS' CONCLUSIONS

We are uncertain about the effect of intrauterine or intraovarian administration of PRP on outcomes of assisted reproduction technology in infertile women. The pooled results should be interpreted with caution. Only one of the 12 included studies was judged at low risk of bias. Other limitations of the included trials were failure to report live birth, poor reporting of methods, lack of prospective protocol registration, low precision due to the small number of enrolled participants, indirectness due to the specific subpopulations and settings studied, and insufficient or absent safety data.

Endometrial biopsy performed before the first in vitro fertilization does not impact the early pregnancy rate

Endometrial biopsy (EB) has been showed to increase the rate of clinical pregnancy in patients who underwent in vitro fertilization (IVF) failures. The purpose of this work was to assess the impact of an EB performed before the first in IVF on the early pregnancy rate. Be One study is a prospective, single-centre, randomized, open-label study. In this parallel study, patients were evenly split into two groups. In one group, patients underwent an EB between days 17 and 22 of the menstrual cycle that precedes the ovarian stimulation. In the other group (control), no EB was performed. The hCG-positive rate (early pregnancy rate) was evaluated on day 14 after the ovarian puncture. In total, 157 patients were randomized in the EB group and 154 patients were in the control group. The early pregnancy rate was 33.1% (52/157) in the EB group and 29.9% (46/154) in the control group (p = 0.54). Other parameters, including perforation, endometritis, or pain level were reassuring. An EB performed during the luteal phase of the menstrual cycle preceding the stimulation of the first IVF did not increase early pregnancy rate.

Fertility specialists' views, behavior, and attitudes towards the use of endometrial scratching in Italy

BACKGROUND

Endometrial scratching (ES) or injury is intentional damage to the endometrium performed to improve reproductive outcomes for infertile women desiring pregnancy. Moreover, recent systematic reviews with meta-analyses and randomized controlled trials demonstrated that ES is not effective, data on the safety are limited, and it should not be recommended in clinical practice. The aim of the current study was to assess the view and behavior towards ES among fertility specialists throughout infertility centers in Italy, and the relationship between these views and the attitudes towards the use of ES as an add-on in their commercial setting.

METHODS

Online survey among infertility centers, affiliated to Italian Society of Human Reproduction (SIRU), was performed using a detailed questionnaire including 45 questions with the possibility to give "closed" multi-choice answers for 41 items and "open" answers for 4 items. Online data from the websites of the infertility centers resulting in affiliation with the specialists were also recorded and analyzed. The quality of information about ES given on infertility centers websites was assessed using a scoring matrix including 10 specific questions (scored from 0 to 2 points), and the possible scores ranged from 0 to 13 points ('excellent' if the score was 9 points or more, 'moderate' if the score was between 5 and 8, and 'poor' if it was 4 points or less).

RESULTS

The response rate was of 60.6% (43 questionnaires / 71 infertility SIRU-affiliated centers). All included questionnaires were completed in their entirety. Most physicians (~ 70%) reported to offer ES to less than 10% of their patients. The procedure is mainly performed in the secretory phase (69.2%) using pipelle (61.5%), and usually in medical ambulatory (56.4%) before IVF cycles to improve implantation (71.8%) without drugs administration (e.g., pain drugs, antibiotics, anti-hemorrhagics, or others) before (76.8%) or after (64.1%) the procedure. Only a little proportion of infertility centers included in the analysis proposes formally the ES as an add-on procedure (9.3%), even if, when proposed, the full description of the indications, efficacy, safety, and costs is never addressed. However, the overall information quality of the websites was generally "poor" ranging from 3 to 8 and having a low total score (4.7 ± 1.6; mean ± standard deviation).

CONCLUSIONS

In Italy, ES is a procedure still performed among fertility specialists for improving the implantation rate in IVF patients. Moreover, they have a poor attitude in proposing ES as an add-on in the commercial setting.

Endometrial injury for pregnancy following sexual intercourse or intrauterine insemination

BACKGROUND

Intentional endometrial injury is being proposed as a technique to improve the probability of pregnancy in women undergoing assisted reproductive technologies (ART) such as in vitro fertilisation (IVF). Endometrial injury is often performed by pipelle biopsy and is a common gynaecological procedure with established safety. However, it causes a moderate degree of discomfort/pain and requires an additional pelvic examination. The effectiveness of this procedure outside of ART, in women or couples attempting to conceive via sexual intercourse or with intrauterine insemination (IUI), remains unclear.

OBJECTIVES

To assess the effectiveness and safety of intentional endometrial injury performed in infertile women or couples attempting to conceive through sexual intercourse or intrauterine insemination (IUI).

SEARCH METHODS

The Cochrane Gynaecology and Fertility Group Specialised Register, CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, LILACS, ISI Web of Knowledge, and clinical trial registries were searched from inception to 21 May 2020, as were conference abstracts and reference lists of relevant reviews and included studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that evaluated any kind of intentional endometrial injury in women planning to undergo IUI or attempting to conceive spontaneously (with or without ovarian stimulation (OS)) compared to no intervention, a mock intervention, or intentional endometrial injury performed at a different time.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. Primary outcomes were live birth/ongoing pregnancy and pain experienced during the procedure. Due to high risk of bias associated with many of the studies, primary analyses of all review outcomes were restricted to studies at low risk of bias. Sensitivity analysis including all studies was then performed.

MAIN RESULTS

We included 22 RCTs (3703 women). Most of these studies included women with unexplained infertility. Intentional endometrial injury versus either no intervention or a sham procedure The primary analysis was restricted to studies at low risk of bias, which left only one study included. We are uncertain whether endometrial injury has an effect on the probability of live birth, as only one study is included in the analysis and the confidence interval is wide (risk ratio (RR) 1.11, 95% confidence interval (CI) 0.78 to 1.59; 1 RCT, 210 participants). Evidence suggests that if the chance of live birth with no intervention/a sham procedure is assumed to be 34%, then the chance with endometrial injury would be 27% to 55%. When all studies were included in the sensitivity analysis, we were uncertain whether endometrial injury improves live birth/ongoing pregnancy, as the evidence was of very low quality (RR 1.71, 95% CI 1.32 to 2.21; 8 RCTs, 1522 participants; I² = 16%). Evidence suggests that if the chance of live birth/ongoing pregnancy with no intervention/a sham procedure is assumed to be 13%, then the chance with endometrial injury would be 17% to 28%. A narrative synthesis conducted for the other primary outcome of pain during the procedure included studies measuring pain on a zero-to-ten visual analogue scale (VAS) or grading pain as mild/moderate/severe, and showed that most often mild to moderate pain was reported (6 RCTs, 911 participants; very low-quality evidence). Timing of intentional endometrial injury Four trials compared endometrial injury performed in the cycle before IUI to that performed in the same cycle as IUI. None of these studies reported the primary outcomes of live birth/ongoing pregnancy and pain during the procedure. One study compared endometrial injury in the early follicular phase (EFP; Day 2 to 4) to endometrial injury in the late follicular phase (LFP; Day 7 to 9), both in the same cycle as IUI. The primary outcome live birth/ongoing pregnancy was not reported, but the study did report the other primary outcome of pain during the procedure assessed by a zero-to-ten VAS. The average pain score was 3.67 (standard deviation (SD) 0.7) when endometrial injury was performed in the EFP and 3.84 (SD 0.96) when endometrial injury was performed in the LFP. The mean difference was -0.17, suggesting that on average, women undergoing endometrial injury in the EFP scored 0.17 points lower on the VAS as compared to women undergoing endometrial injury in the LFP (95% CI -0.48 to 0.14; 1 RCT, 110 participants; very low-quality evidence).

AUTHORS' CONCLUSIONS

Evidence is insufficient to show whether there is a difference in live birth/ongoing pregnancy between endometrial injury and no intervention/a sham procedure in women undergoing IUI or attempting to conceive via sexual intercourse. The pooled results should be interpreted with caution, as the evidence was of low to very low quality due to high risk of bias present in most included studies and an overall low level of precision. Furthermore, studies investigating the effect of timing of endometrial injury did not report the outcome live birth/ongoing pregnancy; therefore no conclusions could be drawn for this outcome. Further well-conducted RCTs that recruit large numbers of participants and minimise bias are required to confirm or refute these findings. Current evidence is insufficient to support routine use of endometrial injury in women undergoing IUI or attempting to conceive via sexual intercourse.

The outcomes of sequential embryo transfer in patients undergoing in vitro fertilization with frozen-thawed embryos: A retrospective study

AIM

To explore whether sequential embryo transfer benefits patients with repeated implantation failure (RIF) undergoing frozen-thawed embryo transfer (FET) cycles.

METHODS

We included 311 patients with a history of RIF in this retrospective study. We did sequential transfers with a cleavage embryo on day 3 and a blastocyst on day 5 in 77 patients; blastocyst transfers with two blastocysts on day 5 in 80 patients; and cleavage embryo transfers with two cleavage embryos on day 3 in 154 patients. We compared clinical outcomes between the three groups.

RESULTS

The clinical pregnancy rate was comparable between the blastocyst transfer group (48.8%), the sequential transfer group(48.1%) and the cleavage embryo transfer group (48.1%). There was no statistically significant difference found (p > 0.05). The ongoing pregnancy and multipregnancy rates were also comparable between the three groups (p > 0.05). The early miscarriage rate was significantly higher in the sequential transfer group (32.4%) compared with the blastocyst group (12.8%) and the cleavage embryo group (12.2%) (p < 0.05). However, after adjusting for confounders, there was no significant difference in early miscarriage rates in the sequential transfer group compared with the blastocyst group (odds ratio [OR], 2.97; 95% confidence interval [CI], 0.85-9.24; p = 0.07) and the cleavage embryo group (OR, 3.03; 95% CI, 0.94-8.06; p = 0.08).

CONCLUSIONS

Sequential embryo transfer failed to improve clinical outcomes for patients with RIF.

Endometrial scratch injury in infertile women seeking conception through natural or intrauterine insemination cycles: A systematic review and meta-analysis

OBJECTIVE

Implantation failure is a major cause of infertility. To evaluate the value of ESI in infertile women undergoing natural or IUI cycles.

METHODS

Screening of MEDLINE, CENTRAL, other bases from inception to June 2021 using the keywords related to endometrial scratch, implantation, infertility, and IUI. RCTs of intentional endometrial injury in couples seeking fertility through natural or IUI cycles were included. All types of ESI with variable intensity (mild to moderate or severe), at different times of the cycle (preceding follicular, preceding luteal, same follicular or two times), single or double compared to none, placebo or other active interventions were included. Twenty-five studies included 4234 women (five natural [774 women], 20 IUI [3460 women]) fulfilled the inclusion criteria. Extracted data included settings of the study, sample size, participant characteristics, intervention details and outcome parameters. The primary outcome was the clinical pregnancy rate.

RESULTS

ESI increased clinical pregnancy rate from 16.1% (62/386) to 26.5% (103/388) and from 11.4% (186/1627) to 22.25% (408/1833), P = 0.004 and <0.001 in natural and IUI cycles, respectively. ESI increased live birth rate from 26.6% (42/158) to 37.6% (59/157) (P = 0.250) and from 11.2% (36/322) to 18% (58/322) (P = 0.020) in natural and IUI cycles, respectively.

CONCLUSION

ESI increased both clinical pregnancy and ongoing pregnancy rates significantly in natural and IUI cycles. However, there is marked methodological heterogeneity among the different studies in defining the outcome parameters.

Intentional endometrial injury enhances angiogenesis through increased production and activation of MMP-9 by TNF-α and MMP-3 in a mouse model

There have been reports of improved pregnancy rates after performing intentional endometrial injuries, also known as endometrial scratching, in patients with recurrent implantation failure. In our previous study on intentional endometrial injury, we found an increased expression of matrix metalloproteinase (MMP)-3 following induced injuries to the mice endometrium. In the current study, we further examine whether the rise in MMP-3 could contribute to increased angiogenesis. Female C57B1/6 mice were obtained at 12 weeks of age, and intentional endometrial injuries were induced mechanically in the left uterine horns. Using the appropriate media, uterine-washes were performed on the injured and uninjured (control) horns of the harvested uteri. The uterine tissues were further processed for tissue lysates, histopathology and immunohistochemistry. The results show that intentional endometrial injuries caused an increase in secreted LPA in the injured horns, which were detected in the uterine-washes. In addition, LPA induced increased production of TNF-α in human endometrial epithelial cells (hEEpCs). Furthermore, TNF-α appeared to induce differential and cell-specific upregulation of the MMPs: MMP-3 was upregulated in the epithelial (hEEpCs), while MMP-9 was upregulated in the endothelial cells (human endometrial endothelial cells; hEEnCs). The upregulation of MMP-3 appeared to be necessary for the activation of MMP-9, whose active form stimulated the formation of vessel-like structure by the hEEnCs. The results of this study suggest that there may be enhanced angiogenesis following intentional endometrial injuries, which is mediated in part by TNF-α-induced and MMP-3-activated MMP-9 production.

Endometrial injury in women undergoing in vitro fertilisation (IVF)

BACKGROUND

Implantation of an embryo within the endometrial cavity is a critical step in the process of in vitro fertilisation (IVF). Previous research has suggested that endometrial injury (also known as endometrial scratching), defined as intentional damage to the endometrium, can increase the chance of pregnancy in women undergoing IVF.

OBJECTIVES

To assess the effectiveness and safety of endometrial injury performed before embryo transfer in women undergoing in vitro fertilisation (IVF) including intracytoplasmic sperm injection (ICSI) and frozen embryo transfer.

SEARCH METHODS

In June 2020 we searched the Cochrane Gynaecology and Fertility Group Specialised Register, CENTRAL, MEDLINE, Embase, CINAHL, LILACS, DARE and two trial registries. We also checked the reference sections of relevant studies and contacted experts in the field for any additional trials.

SELECTION CRITERIA

Randomised controlled trials comparing intentional endometrial injury before embryo transfer in women undergoing IVF, versus no intervention or a sham procedure.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. Two independent review authors screened studies, evaluated risk of bias and assessed the certainty of the evidence by using GRADE (Grading of Recommendation, Assessment, Development and Evaluation) criteria. We contacted and corresponded with study investigators as required. Due to the high risk of bias associated with many of the studies, the primary analyses of all review outcomes were restricted to studies at a low risk of bias for selection bias and other bias. Sensitivity analysis was then performed including all studies. The primary review outcomes were live birth and miscarriage.

MAIN RESULTS

Endometrial injury versus control (no procedure or a sham procedure) A total of 37 studies (8786 women) were included in this comparison. Most studies performed endometrial injury by pipelle biopsy in the luteal phase of the cycle before the IVF cycle. The primary analysis was restricted to studies at low risk of bias, and included eight studies. The effect of endometrial injury on live birth is unclear as the result is consistent with no effect, or a small reduction, or an improvement (odds ratio (OR) 1.12, 95% confidence interval (CI) 0.98 to 1.28; participants = 4402; studies = 8; I² = 15%, moderate-certainty evidence). This suggests that if the chance of live birth with IVF is usually 27%, then the chance when using endometrial injury would be somewhere between < 27% and 32%. Similarly, the effect of endometrial injury on clinical pregnancy is unclear (OR 1.08, 95% CI 0.95 to 1.23; participants = 4402; studies = 8; I² = 0%, moderate-certainty evidence). This suggests that if the chance of clinical pregnancy from IVF is normally 32%, then the chance when using endometrial injury before IVF is between 31% and 37%. When all studies were included in the sensitivity analysis, we were unable to conduct meta-analysis for the outcomes of live birth and clinical pregnancy due to high risk of bias and statistical heterogeneity. Endometrial injury probably results in little to no difference in chance of miscarriage (OR 0.88, 95% CI 0.68 to 1.13; participants = 4402; studies = 8; I² = 0%, moderate-certainty evidence), and this result was similar in the sensitivity analysis that included all studies. The result suggests that if the chance of miscarriage with IVF is usually 6.0%, then when using endometrial injury it would be somewhere between 4.2% and 6.8%. Endometrial injury was associated with mild to moderate pain (approximately 4 out of 10), and was generally associated with some minimal bleeding. The evidence was downgraded for imprecision due to wide confidence intervals and therefore all primary analyses were graded as moderate certainty. Higher versus lower degree of injury Only one small study was included in this comparison (participants = 129), which compared endometrial injury using two different instruments in the cycle prior to the IVF cycle: a pipelle catheter and a Shepard catheter. This trial was excluded from the primary analysis due to risk of bias. In the sensitivity analysis, all outcomes reported for this study were graded as very-low certainty due to risk of bias, and as such we were not able to interpret the study results.

AUTHORS' CONCLUSIONS

The effect of endometrial injury on live birth and clinical pregnancy among women undergoing IVF is unclear. The results of the meta-analyses are consistent with an increased chance, no effect and a small reduction in these outcomes. We are therefore uncertain whether endometrial injury improves the chance of live birth or clinical pregnancy in women undergoing IVF. Endometrial injury does not appear to affect the chance of miscarriage. It is a somewhat painful procedure associated with a small amount of bleeding. In conclusion, current evidence does not support the routine use of endometrial injury for women undergoing IVF.

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.

Endometrial injury for pregnancy following sexual intercourse or intrauterine insemination

BACKGROUND

Intentional endometrial injury is being proposed as a technique to improve the probability of pregnancy in women undergoing assisted reproductive technologies (ART) such as in vitro fertilisation (IVF). Endometrial injury is often performed by pipelle biopsy and is a common gynaecological procedure with established safety. However, it causes a moderate degree of discomfort/pain and requires an additional pelvic examination. The effectiveness of this procedure outside of ART, in women or couples attempting to conceive via sexual intercourse or with intrauterine insemination (IUI), remains unclear.

OBJECTIVES

To assess the effectiveness and safety of intentional endometrial injury performed in infertile women or couples attempting to conceive through sexual intercourse or intrauterine insemination (IUI).

SEARCH METHODS

The Cochrane Gynaecology and Fertility Group Specialised Register, CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, LILACS, ISI Web of Knowledge, and clinical trial registries were searched from inception to 21 May 2020, as were conference abstracts and reference lists of relevant reviews and included studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that evaluated any kind of intentional endometrial injury in women planning to undergo IUI or attempting to conceive spontaneously (with or without ovarian stimulation (OS)) compared to no intervention, a mock intervention, or intentional endometrial injury performed at a different time or to a higher/lower degree.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. Primary outcomes were live birth/ongoing pregnancy and pain experienced during the procedure. Due to high risk of bias associated with many of the studies, primary analyses of all review outcomes were restricted to studies at low risk of bias. Sensitivity analysis including all studies was then performed.

MAIN RESULTS

We included 23 RCTs (4035 women). Most of these studies included women with unexplained infertility. Intentional endometrial injury versus either no intervention or a sham procedure The primary analysis was restricted to studies at low risk of bias, which left only one study included. We are uncertain whether endometrial injury has an effect on the probability of live birth, as only one study is included in the analysis and the confidence interval is wide (risk ratio (RR) 1.11, 95% confidence interval (CI) 0.78 to 1.59; 1 RCT, 210 participants). Evidence suggests that if the chance of live birth with no intervention/a sham procedure is assumed to be 34%, then the chance with endometrial injury would be 27% to 55%. When all studies were included in the sensitivity analysis, we were uncertain whether endometrial injury improves live birth/ongoing pregnancy, as the evidence was of very low quality (RR 1.71, 95% CI 1.32 to 2.21; 8 RCTs, 1522 participants; I² = 16%). Evidence suggests that if the chance of live birth/ongoing pregnancy with no intervention/a sham procedure is assumed to be 13%, then the chance with endometrial injury would be 17% to 28%. A narrative synthesis conducted for the other primary outcome of pain during the procedure included studies measuring pain on a zero-to-ten visual analogue scale (VAS) or grading pain as mild/moderate/severe, and showed that most often mild to moderate pain was reported (6 RCTs, 911 participants; very low-quality evidence). Higher versus lower degree of intentional endometrial injury Evidence was insufficient to show whether there is a difference in ongoing pregnancy rates (RR 1.29, 95% CI 0.71 to 2.35; 1 RCT, 332 participants; low-quality evidence) between hysteroscopy with endometrial injury and hysteroscopy alone. Evidence suggests that if the chance of ongoing pregnancy with hysteroscopy alone is 10%, then the chance with hysteroscopy with endometrial injury would be 7% to 24%. This study did not report the primary outcomes of live birth and pain during the procedure. Timing of intentional endometrial injury Four trials compared endometrial injury performed in the cycle before IUI to that performed in the same cycle as IUI. None of these studies reported the primary outcomes of live birth/ongoing pregnancy and pain during the procedure. One study compared endometrial injury in the early follicular phase (EFP; Day 2 to 4) to endometrial injury in the late follicular phase (LFP; Day 7 to 9), both in the same cycle as IUI. The primary outcome live birth/ongoing pregnancy was not reported, but the study did report the other primary outcome of pain during the procedure assessed by a zero-to-ten VAS. The average pain score was 3.67 (standard deviation (SD) 0.7) when endometrial injury was performed in the EFP and 3.84 (SD 0.96) when endometrial injury was performed in the LFP. The mean difference was -0.17, suggesting that on average, women undergoing endometrial injury in the EFP scored 0.17 points lower on the VAS as compared to women undergoing endometrial injury in the LFP (95% CI -0.48 to 0.14; 1 RCT, 110 participants; very low-quality evidence).

AUTHORS' CONCLUSIONS

Evidence is insufficient to show whether there is a difference in live birth/ongoing pregnancy between endometrial injury and no intervention/a sham procedure in women undergoing IUI or attempting to conceive via sexual intercourse. The pooled results should be interpreted with caution, as the evidence was of low to very low quality due to high risk of bias present in most included studies and an overall low level of precision. Furthermore, studies investigating the effect of timing of endometrial injury did not report the outcome live birth/ongoing pregnancy; therefore no conclusions could be drawn for this outcome. Further well-conducted RCTs that recruit large numbers of participants and minimise bias are required to confirm or refute these findings. Current evidence is insufficient to support routine use of endometrial injury in women undergoing IUI or attempting to conceive via sexual intercourse.

The cytokine profile of menstrual blood

Introduction

The menstrual cycle is regulated by a complex interplay between endometrial epithelial cells, endothelial cells, immune cells, and sex hormones. To communicate, cells secrete cytokines that have multiple and diverse effects on recipient cells. Knowledge of how these cells interact in the uterus is insufficient. Menstrual blood is easily accessible and provides a source to study menstrual cycle physiology. This study aimed to determine the cytokine profile in menstrual blood plasma and investigate the differences in cytokine profiles between menstrual and peripheral blood plasma. Several previous studies indicate an improved chance of embryo implantation after endometrial scratching. Consequently, our secondary aim was to compare the menstrual blood cytokine profile before and after luteal phase endometrial scratching.

Material and methods

Nineteen healthy donors collected menstrual blood for the first 24 hours of menstruation in two sequential cycles. Matched peripheral blood was taken at the same time. An endometrial biopsy was performed at cycle day 7‐9 post ovulation in between the two collection times. A Luminex multiplex assay was performed in one batch analyzing a predetermined group of cytokines in plasma.

Results

Peripheral blood plasma and menstrual blood plasma showed substantial significant differences in cytokine profile. In menstrual blood plasma, C5/C5a, interleukin‐6 (IL‐6), IL‐1β, and CXCL8 were detected in high concentrations, whereas IL‐2, IL‐12p70, XCL1/Lymphotactin, and interferon‐γ were low. The most pronounced median differences between menstrual and peripheral blood plasma were found for IL‐6, IL‐1β, and CXCL8. The cytokine profiles of menstrual blood plasma were similar between the individual donors and did not differ over two subsequent cycles. None of the cytokines analyzed in menstrual blood plasma differed significantly before or after luteal phase endometrial scratching (P < .01).

Conclusions

Our results demonstrate that the menstrual blood cytokine profile is distinctly different from peripheral blood plasma and that the inter‐individual difference in menstrual blood cytokine profile in healthy donors is limited and stable over time. The small injury caused by an endometrial biopsy does not change the cytokine profile in the subsequent menstrual cycle. Our study provides new insights into menstrual cycle physiology.

Intentional endometrial injury increases embryo implantation potentials through enhanced endometrial angiogenesis†

Embryo implantation rates have been found to be enhanced by precedent endometrial injuries, but the underlying mechanism is not fully investigated. Endometrial inflammation occurs both at peri-implantation period and after endometrial injury, in which vascular reaction is a distinctive feature of inflammation. In this study, intentional endometrial injury was done with a 0.7-mm-diameter brush inserted into the left uterine horn of female ICR mice, then turned around 720° (group 2), and the right uterine horn served as the controls without endometrial injuries (group 1). Intraperitoneal equine chorionic gonadotropin 2.5 IU was injected, followed by human chorionic gonadotropin 10 IU injection, and the uterus was dissected 5 days later, roughly at the peri-implantation period. The peri-implantation endometrium was obtained, and angiogenesis protein array revealed that matrix metalloproteinase-3 (MMP-3), plasminogen activator inhibitor-1 (PAI-1), insulin-like growth factor binding protein 1 (IGFBP-1), and IL-1α were more strongly expressed in injured endometrium (group 2) than in the controls (group 1). Immunohistochemical CD34 staining was more prominently expressed in group 2 uterus, and the treatment with LY294002, a phosphoinositide 3-kinase (PI3K) inhibitor, significantly decreased CD34 immunopositive cells. The capabilities of permeability, proliferation, tube formation, and migration of mouse endometrial endothelial cells were significantly enhanced in group 2 than in group 1. Our results demonstrate that enhanced endometrial angiogenesis is a possible mechanism accounting for the increased endometrial receptivity after endometrial injury.

First trimester neutrophil-to-lymphocyte ratio (NLR) and pregnancy outcomes in medically assisted reproduction (MAR): a case control study

As success rates after medically assisted reproduction (MAR) technologies have remained constantly limited during the last years, there has been a systematic effort to predict clinical outcomes. There is currently weak evidence to name the neutrophil-to-lymphocyte ratio (NLR), as an accurate predictor in MAR. Through a case control study, and by setting strict eligibility criteria, we enrolled 66 women (35 with negative outcome and 31 cycles with live birth), in terms of NLR at the time of oocyte retrieval. Clinical and IVF cycle characteristics were comparable in a normalized population. There was a positive correlation between NLR and the age of the woman (r = 0.310, p=.011 and rs =0.363, p=.033). Higher odds ratios (ORs) of MAR positive outcome were detected only at higher NLR values, when NLR was divided into quartiles, but only in the 4th quartile [OR =4.33 (95%CI: 1.02-10.79)]. ROC curve resulted on an AUC equal to 0.660 (95%CI: 0.529-0.791) and p value .025. The estimated specificity, sensitivity and cutoff point were 0.57, 0.548, and 1.98, respectively, while PPV and NPV values were 70.6% and 59.3%, respectively. In conclusion, NLR was positively correlated with maternal age; in our study cohort, MAR failure was associated with lower NLR values.

Does endometrial scratching increase the rate of spontaneous conception in couples with unexplained infertility and a good prognosis (Hunault > 30%)? Study protocol of the SCRaTCH-OFO trial: a randomized controlled trial

Background

In the Netherlands, couples with unexplained infertility and a good prognosis to conceive spontaneously (i.e. Hunault > 30%) are advised to perform timed intercourse for at least another 6 months. If couples fail to conceive within this period, they will usually start assisted reproductive technology (ART). However, treatment of unexplained infertility by ART is empirical and can involve significant burdens. Intentional endometrial injury, also called ‘endometrial scratching’, has been proposed to positively affect the chance of embryo implantation in patients undergoing in vitro fertilization (IVF). It might also be beneficial for couples with unexplained infertility as defective endometrial receptivity may play a role in these women. The primary aim of this study is to determine whether endometrial scratching increases live birth rates in women with unexplained infertility.

Method

A multicentre randomized controlled trial will be conducted in Dutch academic and non-academic hospitals starting from November 2017. A total of 792 women with unexplained infertility and a good prognosis for spontaneous conception < 12 months (Hunault > 30%) will be included, of whom half will undergo endometrial scratching in the luteal phase of the natural cycle. The women in the control group will not undergo endometrial scratching. According to Dutch guidelines, both groups will subsequently perform timed intercourse for at least 6 months. The primary endpoint is cumulative live birth rate. Secondary endpoints are clinical and ongoing pregnancy rate; miscarriage rate; biochemical pregnancy loss; multiple pregnancy rate; time to pregnancy; progression to intrauterine insemination (IUI) or IVF; pregnancy complications; complications of endometrial scratching; costs and endometrial tissue parameters associated with reproductive success or failure. The follow-up duration is 12 months.

Discussion

Several small studies show a possible beneficial effect of endometrial scratching in women with unexplained infertility trying to conceive naturally or through IUI. However, the quality of this evidence is very low, making it unclear whether these women will truly benefit from this procedure. The SCRaTCH-OFO trial aims to investigate the effect of endometrial scratching on live birth rate in women with unexplained infertility and a good prognosis for spontaneous conception < 12 months.

Trial registration

NTR6687, registered August 31st, 2017.

Protocol version

Version 2.6, November 14th, 2018.

Endometrial injury for patients with endometriosis and polycystic ovary syndrome undergoing medically assisted reproduction: current data and a protocol

We propose a study protocol capable of improving clinical outcomes following medically assisted reproduction (MAR) in infertile women with endometriosis and polycystic ovary syndrome (PCOS). The proposed research derives from the published evidence on the positive impact from endometrial injury (EI) and the beneficial nature of the intervention towards improved implantation rates. We primarily refer to the cluster of events and hypotheses, such as the mechanical cascade, the inflammatory response per se, the events accompanying wound healing, the immune cell recruitment and protein involvement, alterations in gene expression and the neo-angiogenesis theories, which have been previously investigated for this purpose. We are also exploring the possible problems in MAR cycles with negative outcomes in PCOS and endometriosis patients and we are proposing potential mechanisms on how this intervention might work. Our hypothesis states that the EI before the initiation of the MAR cycle can affect clinical pregnancy rates in patients with the aforementioned pathologies.

Randomized controlled trial of the effect of endometrial injury on implantation and clinical pregnancy rates during the first ICSI cycle

OBJECTIVE

To assess whether endometrial injury in the cycle preceding controlled ovarian hyperstimulation during intracytoplasmic sperm injection (ICSI) improves the implantation and pregnancy rates.

METHODS

Between January 1, 2016, and March 31, 2017, a randomized controlled trial was conducted at a center in Egypt among 300 women who met inclusion criteria (first ICSI cycle, aged <40 years, day-3 follicle-stimulating hormone <10 IU/L, normal serum prolactin, no uterine cavity abnormality). The women were randomly allocated using a web-based system to undergo endometrial scratch in the cycle preceding controlled ovarian hyperstimulation (n=150) or to a control group (n=150). Only data analysts were masked to group assignment. The primary outcomes were the implantation and clinical pregnancy rates at 14 days and 4 weeks after embryo transfer, respectively. Analyses were by intention to treat.

RESULTS

The implantation rate was significantly higher in the endometrial scratch group (41.3% [90/218]) than in the control group (30.0% [63/210]; P<0.001). The clinical pregnancy rate was also significantly higher in the endometrial scratch group (44.2% [61/138]) than in the control group (30.4% [41/135]; P<0.001).

CONCLUSION

Endometrial injury in the cycle preceding the stimulation cycle improved implantation and pregnancy rates during ICSI. CLINICALTRIALS.GOV: NCT02660125.

Therapeutic Efficacy of Endometrial Scratching in Repeated Controlled Ovarian Stimulation (COS) Failure Cycles

Objective:

The objective of the study was (1) “to evaluate the therapeutic efficacy of endometrial scratching in repeated controlled ovarian stimulation (COS) failure cycles.” And (2) “to compare differences in pregnancy outcome by endometrial scratching in early (D2–D4) and late follicular phases (D7–D9) of the same stimulation cycle.”

Materials and Methods:

Women attending infertility clinic in a tertiary care center and who have two or more repeated COS failure cycles and planned for COS with intrauterine insemination (IUI) were included in the study which is a prospective parallel, interventional, single-blinded, randomized control study, in 1:1 allocation ratio. A total of 165 patients were recruited and randomly allocated into three groups: Group A (n = 55) underwent endometrial scratching on D2–D4 of the same COS cycle, Group B (n = 55) on D7–D9, and Group C (n = 55) no intervention done. All the patients underwent COS according to standard protocol followed by IUI.

Results:

Clinical pregnancy rate was 12.73% (odds ratio [OR] =0.87 95% confidence interval [CI] =0.288–2.55, P = 1), 16.36% (OR = 1.15; 95% CI = 0.40–3.23, P = 1), and 14.54%, respectively, in Group A, B, and C, respectively (P = 0.86), as per intention to treat analysis. Using Chi-square test, P value between Group A and B was 0.787, between Group A and C was 1.000, and between Group B and C was 1.000. As per protocol analysis, clinical pregnancy rate was 13.46% (OR = 0.83; 95% CI = 0.27–2.5, P = 0.74), 19.57% (OR = 1.3 95%; CI = 0.45–3.73, P = 0.41), and 15.69%. Using Chi-square test, Pvalue between Group A and B was 0.588, between Group A and C was 0.967, and between Group B and C was 0.815. No abortions and multiple pregnancies occurred in either of the groups.

Conclusion:

The effect found was of good quantum in Group B as per protocol analysis which could be of clinical relevance if larger sample size would have been taken. Endometrial scratching is a cost-effective and easy technique which may improve clinical pregnancy rates in previous COS failure cycles, but more trials are needed to be conducted using larger sample size to achieve the improved and significant outcome.

Endometrial injury for RIF patients undergoing IVF/ICSI: a prospective nonrandomized controlled trial

To evaluate the effect of endometrial injury on clinical outcomes in subfertile women with repeated implantation failures (RIF) undergoing assisted reproduction. In this prospective nonrandomized controlled trial, 103 subfertile women with RIF were included. Fifty-one underwent endometrial injury through hysteroscopy in the early follicular phase of the previous cycle and 52 underwent the standard protocol without any intervention. Live birth and miscarriage were the primary outcomes. Clinical and in vitro fertilization (IVF) cycle characteristics, were also compared between groups. Both groups were comparable in terms of baseline and cycle characteristics. Live birth rates were significantly higher in the study, compared with the control group (18/51 vs. 8/52, odds ratio (OR) = 0.25; 95% confidence interval (CI) = 0.10-0.64; p = 0.020), although miscarriage rates were similar (7/51 vs. 10/52, OR= 0.25; 95%CI= 0.12-0.66; p = 0.452). The rest of the outcomes parameters were comparable between groups. Logistic regression analysis revealed that endometrial injury and duration of subfertility were independent predictors of live birth after control of other variables (OR = 2.818; 95%CI = 1.044-7.605; p = 0.041 and OR = 0.674; 95%CI = 0.461-0.985, p = 0.042, respectively). Endometrial injury induced through office hysteroscopy in the preceding cycle in subfertile women with RIF improves live birth rates.

Endometrial injury for pregnancy following sexual intercourse or intrauterine insemination

BACKGROUND

Intentional endometrial injury is currently being proposed as a technique to improve the probability of pregnancy in women undergoing assisted reproductive technologies (ART) such as in vitro fertilisation (IVF). Endometrial injury is often performed by pipelle biopsy or a similar technique, and is a common, simple, gynaecological procedure that has an established safety profile. However, it is also known to be associated with a moderate degree of discomfort/pain and requires an additional pelvic examination. The effectiveness of this procedure outside of ART, in women or couples attempting to conceive via sexual intercourse or with low complexity fertility treatments such as intrauterine insemination (IUI) and ovulation induction (OI), remains unclear.

OBJECTIVES

To evaluate the effectiveness and safety of intentional endometrial injury in subfertile women and couples attempting to conceive through sexual intercourse or intrauterine insemination (IUI).

SEARCH METHODS

We searched the Cochrane Gyanecology and Fertility Group Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, PsycINFO, CINAHL, LILACS, DARE, ISI Web of Knowledge and ClinicalTrials.gov; as well as reference lists of relevant reviews and included studies. We performed the searches from inception to 31 October 2015.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that evaluated any kind of intentional endometrial injury in women planning to undergo IUI or attempting to conceive spontaneously (with or without OI) compared to no intervention, a mock intervention or intentional endometrial injury performed at a different time or to a higher/lower degree.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, extracted data and assessed trial quality using GRADE methodology. The primary outcomes were live birth/ongoing pregnancy and pain experienced during the procedure. Secondary outcomes were clinical pregnancy, miscarriage, ectopic pregnancy, multiple pregnancy and bleeding secondary to the procedure. We combined data to calculate pooled risk ratios (RRs) and 95% confidence intervals (CIs). Statistical heterogeneity was assessed using the I(2) statistic.

MAIN RESULTS

Nine trials, which included a total of 1512 women, met the inclusion criteria of this Cochrane review. Most of these studies included women with unexplained infertility. In seven studies the women were undergoing IUI and in two studies the women were trying to conceive from sexual intercourse. Eight trials compared intentional endometrial injury with no injury/placebo procedure; of these two trials also compared intentional endometrial injury in the cycle prior to IUI with intentional endometrial injury in the IUI cycle. One trial compared higher vs. lower degree of intentional endometrial injury. Intentional endometrial injury vs. either no intervention or a sham procedureWe are uncertain whether endometrial injury improves live birth/ongoing pregnancy as the quality of the evidence has been assessed as very low (risk ratio (RR) 2.22, 95% confidence interval (CI) 1.56 to 3.15; six RCTs, 950 participants; I² statistic = 0%, very low quality evidence). When we restricted the analysis to only studies at low risk of bias the effect was imprecise and the evidence remained of very low quality (RR 2.64, 95% CI 1.03 to 6.82; one RCT, 105 participants; very low quality evidence). Endometrial injury may improve clinical pregnancy rates however the evidence is of low quality (RR 1.98, 95% CI 1.51 to 2.58; eight RCTs, 1180 participants; I² statistic = 0%, low quality evidence).The average pain experienced by participants undergoing endometrial injury was 6/10 on a zero-10 visual analogue scale (VAS)(standard deviation = 1.5). However, only one study reported this outcome. Higher vs. lower degree of intentional endometrial injuryWhen we compared hysteroscopy with endometrial injury to hysteroscopy alone, there was no evidence of a difference in ongoing pregnancy rate (RR 1.29, 95% CI 0.71 to 2.35; one RCT, 332 participants; low quality evidence) or clinical pregnancy rate (RR 1.15, 95% CI 0.66 to 2.01; one RCT, 332 participants, low quality evidence). This study did not report the primary outcome of pain during the procedure. Timing of intentional endometrial injuryWhen endometrial injury was performed in the cycle prior to IUI compared to the same cycle as the IUI, there was no evidence of a difference in ongoing pregnancy rate (RR 0.65, 95% CI 0.37 to 1.16, one RCT, 176 participants; very low quality evidence) or clinical pregnancy rate (RR 0.82, 95% CI 0.50 to 1.36; two RCTs, 276 participants; very low quality evidence). Neither of these studies reported the primary outcome of pain during the procedure.In all three comparisons there was no evidence of an effect on miscarriage, ectopic pregnancy or multiple pregnancy. No studies reported bleeding secondary to the procedure.

AUTHORS' CONCLUSIONS

It is uncertain whether endometrial injury improves the probability of pregnancy and live birth/ongoing pregnancy in women undergoing IUI or attempting to conceive via sexual intercourse. The pooled results should be interpreted with caution as we graded the quality of the evidence as either low or very low. The main reasons we downgraded the quality of the evidence were most included studies were at a high risk of bias and had an overall low level of precision. Further well-conducted RCTs that recruit large numbers of participants and minimise internal bias are required to confirm or refute these findings.

Pipelle for Pregnancy (PIP): study protocols for three randomised controlled trials

Background

The success rate of infertility treatments remains modest. Endometrial injury has been suggested as an intervention to increase the probability of pregnancy in women undergoing assisted reproductive technologies such as in vitro fertilisation (IVF). The majority of studies and systematic reviews have reported that endometrial injury improves the outcomes of IVF, intrauterine insemination and natural conception; however, the size and quality of the studies are poor. The low quality of the available evidence questions the presence of any real beneficial effect, and the applicability of the intervention in different populations remains unclear.

Methods/design

The PIP trials are three multi-centre, randomised controlled trials designed to test three separate hypotheses: whether endometrial injury increases the probability of live birth in women or couples

1) who are undergoing autologous embryo transfer as part of an IVF cycle (PIP-IVF),

2) with unexplained infertility who are attempting to conceive naturally (PIP-UE) and

3) with subfertility related to polycystic ovarian syndrome (PCOS) who are on ovulation induction medication and attempting to conceive (PIP-PCOS).

Participants will be randomised to either undergo endometrial injury by endometrial pipelle biopsy or to:

• no intervention (PIP-IVF), or

• a sham procedure (PIP-PCOS and PIP-UE).

In PIP-IVF, endometrial injury will be carried out between day three of the cycle prior to the IVF cycle, and day three of the IVF cycle. In PIP-UE and PIP-PCOS, endometrial injury or a sham procedure will be undertaken between days 1–12 of a menstrual cycle or ovulation induction cycle respectively. Participants in PIP-UE and PIP-PCOS will then be followed for three cycles during which time they will attempt to conceive from sexual intercourse. To ensure allocation concealment, randomisation will be carried out using a web-based system or sequentially numbered, opaque, sealed envelopes. The primary outcome is live birth. Secondary outcomes include ongoing pregnancy, clinical pregnancy and miscarriage.

The required sample sizes for the PIP studies have been estimated at 840 (PIP-IVF), 350 (PIP-UE) and 280 (PIP-PCOS). Primary analysis will be as per intention-to-treat principles.

Discussion

The PIP trials are designed to address the gaps in the utility of endometrial scratching as a treatment for subfertility in three different populations. If the beneficial effect of this intervention can be confirmed in these settings, endometrial scratching will provide a cost-effective method for helping women and couples to conceive.

Trial registrations

PIP-IVF ACTRN12614000626662 registered 13/6/2014; PIP-PCOS ACTRN12614000657628 registered 24/6/2014; PIP-UE ACTRN12614000656639 registered 24/6/2014. The trials are ongoing.

Why Prospectively Randomized Clinical Trials Have Been Rare in Reproductive Medicine and Will Remain So?

There is almost unanimity that modern medicine should be "evidence based." In this context, lack of prospectively randomized clinical trials (RCTs) is widely lamented in reproductive medicine. Some leading voices, indeed, increasingly suggest that only RCT-based clinical conclusions should be integrated into clinical practice, since lower levels of evidence are inadequate. We have argued that reproductive medicine requires special considerations because, like clinical oncology, fertility treatments (especially in older women) are time dependent. Unlike clinical oncology, reproductive medicine, however, does not receive substantial financial research support from government or industry and, at least in the United States, has, therefore, to be primarily funded via patient revenues. Given a 50% chance of receiving placebo, infertility patients are, understandably, reluctant to fund their own RCTs. We here selectively review this subject, contrasting opposing opinions recently published in the literature by a prominent reproductive scientist and one of the world's leading experts on evidence-based medicine. Placing these recent publications into the evolving context of infertility practice, as also addressed in this journal in recent publications, we conclude that objective reasons explain why relatively few RCTs are performed in reproductive medicine and predict that this will not change in the foreseeable future. Reproductive medicine, therefore, has to find ways to develop satisfactory clinical evidence in other ways, satisfying patients' rights to easy access to potentially beneficial medical treatments with low costs and low risks. The RCTs should be reserved for relatively high risk and/or high cost treatments.

Morphological Changes and Expression of Cytokine After Local Endometrial Injury in a Mouse Model

OBJECTIVE

To establish a mouse model for endometrial injury and determine the underlying mechanism regarding its favorable effect on embryo implantation.

STUDY DESIGN

Female Kunming mice were randomly allocated into 4 groups: group I, normal control; group II, injury procedure control; and group III and group IV, the mice being scratched with a blunt syringe on the right uterine horn or both, respectively. All the mice were mated with the males during the next estrus phase. The number of implanted embryos on each side of uterus was calculated on day 8 of pregnancy. The endometrial samples were taken on day 4 of pregnancy, and the local morphological changes and cytokine expressions were examined.

RESULTS

Compared to group II, our results showed that in group IV (1) there were significantly higher numbers of implanted embryos, (2) the endometrial glands and vasculatures in stroma were obviously increased and the pinopodes were abundant and well developed, and (3) the local levels of cytokines leukemia inhibitory factor (LIF) and oncostatin M (OSM) messenger RNA and protein expression were significantly increased.

CONCLUSIONS

Local mechanical injury on mouse uteri enhanced endometrial receptivity and improved embryo implantation, which were correlated with the characteristic changes in endometrial morphology and the upregulation of LIF and OSM gene and protein expression.

Endometrial injury in women undergoing assisted reproductive techniques

BACKGROUND

Implantation of an embryo within the endometrial cavity is a critical step in assisted reproductive techniques (ART). Previous research has suggested that endometrial injury - intentional damage to the endometrium - can increase the probability of pregnancy in women undergoing ART.

OBJECTIVES

To assess the effectiveness and safety of endometrial injury performed before embryo transfer in women undergoing ART.

SEARCH METHODS

We searched the Cochrane Menstrual Disorders and Subfertility Group (MDSG) Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), the Database of Abstracts of Reviews of Effects (DARE), MEDLINE, EMBASE, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), Latin American Caribbean Health Sciences Literature (LILACS) and ClinicalTrials.gov. The original search was performed in November 2011, and further searches were done in March 2014 and January 2015.

SELECTION CRITERIA

Randomised controlled trials comparing intentional endometrial injury before embryo transfer in women undergoing ART, versus no intervention or a sham procedure.

DATA COLLECTION AND ANALYSIS

Two independent review authors screened studies and extracted data which were checked by a third review author. Two review authors independently assessed risk of bias. We contacted and corresponded with study investigators as required and analysed data using risk ratio (RR) and a random-effects model. We assessed the quality of the evidence by using GRADE (Grades of Recommendation, Assessment, Development and Evaluation) criteria.

MAIN RESULTS

We included 14 trials that included 1063 women in the intervention groups and 1065 women in the control groups. Thirteen studies compared endometrial injury performed between day 7 of the previous cycle and day 7 of the embryo transfer (ET) cycle versus no injury, and one study compared endometrial injury on the day of oocyte retrieval versus no injury. Overall, eight of the 14 included studies were deemed to be at high risk of bias in at least one domain.In studies comparing endometrial injury performed between day 7 of the previous cycle and day 7 of the ET cycle versus no intervention or a sham procedure, endometrial injury was associated with an increase in live birth or ongoing pregnancy rate: RR 1.42, 95% confidence interval (CI) 1.08 to 1.85; P value 0.01; nine RCTs; 1496 women; I² = 53%; moderate-quality evidence. In other words, moderate-quality evidence suggests that if 26% of women achieve live birth without endometrial injury, between 28% and 48% will achieve live birth with endometrial injury. A sensitivity analysis removing the studies at high risk of bias showed no difference in effect.There was no evidence of an effect on miscarriage, however the evidence is of low-quality: RR 0.99, 95% CI 0.63 to 1.53; P value 0.06; eight RCTs; 500 clinical pregnancies; I² = 10%; low-quality evidence.Endometrial injury was also associated with an increased clinical pregnancy rate: RR 1.34, 95% CI 1.21 to 1.61; P value 0.002; 13 RCTs; 1972 women; I² = 45%; moderate-quality evidence. This suggests that if 30% of women achieve clinical pregnancy without endometrial injury, between 33% and 48% will achieve clinical pregnancy with this intervention.Endometrial injury was associated with increased pain, however the evidence was of very low quality. One study reported pain on a VAS scale: MD 4.60, 95% CI 3.98 to 5.22; P value < 0.00001; one RCT; 158 women. Two studies reported the number of pain complaints after the procedure; one recorded no events in either group, and the other reported that endometrial injury increased pain complaints: OR 8.65, 95% CI 2.49 to 30.10; P value 0.0007; one RCT; 101 women.Results from the only randomised controlled trial (RCT) comparing endometrial injury on the day of oocyte retrieval versus no injury, reported that this endometrial injury markedly decreased live birth (RR 0.31, 95% CI 0.14 to 0.69; P value 0.004; 156 women; low-quality evidence) and clinical pregnancy (RR 0.36, 95% CI 0.18 to 0.71; P value 0.003; one RCT; 156 women; low-quality evidence).

AUTHORS' CONCLUSIONS

Moderate-quality evidence indicates that endometrial injury performed between day 7 of the previous cycle and day 7 of the embryo transfer (ET) cycle is associated with an improvement in live birth and clinical pregnancy rates in women with more than two previous embryo transfers. There is no evidence of an effect on miscarriage, multiple pregnancy or bleeding. The procedure is mildly painful. Endometrial injury on the day of oocyte retrieval is associated with a reduction of clinical and ongoing pregnancy rates.Although current evidence suggests some benefit of endometrial injury, we need evidence from well-designed trials that avoid instrumentation of the uterus in the preceding three months, do not cause endometrial damage in the control group, stratify the results for women with and without recurrent implantation failure (RIF) and report live birth.