Injury to the endometrium prior to the frozen–thawed embryo transfer cycle improves pregnancy rates in patients with repeated implantation failure

Aim This retrospective cohort study evaluated the effectiveness of injury to the endometrium prior to the frozen–thawed embryo transfer (FET) cycle in patients with repeated implantation failure (RIF) in our clinic. Methods Included in this study were 173 patients, aged ≤ 41 years, who failed to become pregnant after repeating fair and/or good embryo transfer more than twice between February 2012 and February 2015. The patients were divided into three groups: Group A (n = 38) underwent soft curettage to the endometrium twice, prior to the FET cycle; Group B (n = 45) underwent hysteroscopy prior to the FET cycle, with no significant factors, such as endometrial polyp; and Group C (n = 90) was the no-treatment group. Results The clinical pregnancy rate per transfer was found to be statistically significant between Group A at 42.1% (16/38) and Group C at 22.2% (20/90). The crude and adjusted odds ratios (OR) were 2.55 and 2.49 (95% confidence intervals 1.13–5.78, P = 0.03 and 1.01–6.17, P = 0.048) respectively. Group B with only hysteroscopy had a higher pregnancy rate of 35.6% (16/45) than Group C, but showed no statistical significance (P = 0.103). Conclusion These results suggest that injuring the endometrium has a positive effect on pregnancy.