Endometrial scratch injury for women with one or more previous failed embryo transfers: a systematic review and meta-analysis of randomized controlled trials

Objective: To investigate endometrial scratch injury (ESI) as an intervention to improve IVF outcome in women with a history of ET failure. Design: Systematic review and meta-analysis. Setting: Not applicable. Patient(s): Infertile women undergoing IVF after one or more failed ET. Intervention(s): We included all randomized controlled trials of women undergoing IVF after one or more failed ET, where the intervention group received ESI and controls received placebo or no intervention. Pooled results were expressed as relative risk (RR) with a 95% confidence interval (95% CI). The review protocol was registered in PROSPERO before starting the data extraction (CRD42017082777). Main Outcome Measure(s): Live birth rate (LBR), clinical pregnancy rate (PR), multiple PR, miscarriage rate, ectopic pregnancy (EP) PR. Result(s): Ten studies were included (1,468 participants). The intervention group showed higher LBR (RR 1.38, 95% CI 1.05–1.80) and clinical PR (RR 1.34, 95% CI 1.07–1.67) in comparison to controls, without difference in terms of multiple PR, miscarriage rate, and EP PR. Double luteal ESI with pipelle was associated with the greatest effect on LBR (RR 1.54, 95% CI 1.10–2.16) and clinical PR (RR 1.30, 95% CI 1.03–1.65). The ESI was beneficial for patients with two or more previous ET failure, but not for women with a single previous failed ET. No effect was found in women undergoing frozen-thawed ET cycles. Conclusion(s): The ESI may improve IVF success in patients with two or more previous ET failures undergoing fresh ET. The ESI timing and technique seem to play a crucial role in determining its effect on embryo implantation.