Endometrial injury in women undergoing in vitro fertilisation (IVF)

RATIONALE: Implantation of an embryo within the endometrial cavity is a critical step in the process of in vitro fertilisation (IVF). Research suggests 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. The procedure involves placing a thin plastic tube into the uterus to create a small injury (called a 'scratch') in the lining of the womb. This is an update of a 2021 Cochrane review. OBJECTIVES: To assess the effectiveness and safety of endometrial injury performed before embryo transfer versus no procedure or a sham in women undergoing in vitro fertilisation (IVF) including intracytoplasmic sperm injection (ICSI) and frozen embryo transfer. SEARCH METHODS: We searched CENTRAL, MEDLINE, Embase, PsycInfo, CINAHL, LILACS, and Epistemonikos to 11 December 2025. We also handsearched two trial registries to 3 September 2024, and checked the references of relevant studies. ELIGIBILITY CRITERIA: Randomised controlled trials (RCTs) comparing intentional endometrial injury before embryo transfer in women undergoing IVF, versus no intervention, a sham procedure, or a different frequency of the injury (i.e. one injury versus two injuries). There was no restriction on the language or date of the studies. OUTCOMES: The outcomes of interest were live birth, clinical pregnancy, miscarriage, and adverse effects (such as pain, bleeding, and multiple pregnancy). RISK OF BIAS: We assessed the risk of bias using the Cochrane risk of bias assessment tool, RoB 1. Additionally, we used the TRACT checklist, an integrity tool, to help identify any other potential sources of bias. We documented any concerns identified through the TRACT checklist in the characteristics of included studies. SYNTHESIS METHODS: We used standard methodological procedures recommended by Cochrane. Two review authors independently screened studies, extracted data from included studies, evaluated the risk of bias, and assessed the certainty of the evidence by using GRADE criteria. We contacted and corresponded with study investigators as required. Due to the high risk of bias associated with many included studies, we restricted the primary analyses of all review outcomes to studies at a low risk of bias for selection bias and other bias. We then performed sensitivity analyses, including all studies. INCLUDED STUDIES: We included a total of 24 RCTs with 7234 women. SYNTHESIS OF RESULTS: = 0%; 8 studies, 4402 participants; low-certainty evidence). The result suggests that if the chance of miscarriage with IVF is usually 6%, then when using endometrial injury it would be somewhere between 4% and 7%. Endometrial injury probably results in mild to moderate pain (moderate-certainty evidence). We rated the evidence for the primary analyses of live birth and clinical pregnancy as moderate certainty. However, for miscarriage, we downgraded the certainty of the evidence for imprecision due to wide CIs, and therefore graded it as low certainty. Different number of interventions We only included two studies in this comparison (40 women), which compared one endometrial injury versus two injuries prior to IVF. This comparison did not have a primary analysis due to risk of bias. In the sensitivity analysis, we assessed the certainty of the evidence for all outcomes reported for this study as very-low certainty due to risk of bias, indirectness, and imprecision. As such, it is unclear whether one injury versus two injuries prior to IVF has an effect on the chance of having a baby from IVF, achieving pregnancy, or miscarriage. AUTHORS' CONCLUSIONS: The effect of endometrial injury on live birth and clinical pregnancy amongst 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 may result in little to no difference in chance of miscarriage. The conclusion of the current review did not change from the previous review. FUNDING: This review did not receive any specific funding. REGISTRATION: Protocol (2007) DOI: 10.1002/14651858.CD009517 Review (2012) DOI: 10.1002/14651858.CD009517.pub2 Review (2015) DOI: 10.1002/14651858.CD009517.pub3 Review (2021) DOI: 10.1002/14651858.CD009517.pub4.