Cumulative live birth rates in egg donor IVF cycles with or without endometrial scratching: Is there a residual effect in subsequent embryo transfers? Follow-up results of a RCT in clinical practice.

Introduction: Endometrial scratching (ES) is a simple technique that has been claimed to improve pregnancy rates in patients undergoing assisted reproduction techniques. Our objective was to acknowledge the effects of ES in subsequent embryo transfers by assessing the cumulative live birth rates (LBR) in patients undergoing egg-donor in vitro fertilization (IVF).

Material And Methods: We performed a follow-up analysis of the cumulative reproductive outcomes of the 352 patients included in the Endoscratch Trial (NCT03108157) during the twelve months following the randomization date. We compared the outcomes of patients who underwent an ES for the second and/or successive embryo transfers versus those who did not have an ES performed, in order to determine a possible carry over effect that could lead to different LBR in these groups.

Results: Our analysis reveals that both groups (with and without ES performed before the first embryo transfer) had similar cumulative LBR (69.9% vs 65.9% in group A and B respectively, RR: 1.20, 95% confidence interval (CI): 0.92 - 1.22, p = 0.42). When we analyzed the results comparing patients who had received at least an ES before any of the embryo transfers during that period, we did not find any differences in LBR either (68.0% in patients with at least an ES and 67.8% in patients without ES, RR 1.00, 95%CI 0.87 - 1.16, p = 0.96).

Conclusion: According to our results, we cannot state that ES has a long term effect on endometrial receptivity of egg recipients as cumulative LBR do not differ from those of patients who do not receive it.