the effects of endometrial injury on intrauterine insemination outcome: a randomized clinical trial

background: implantation is considered as the rate-limiting step in success of assisted reproduction techniques, and intrauterine insemination cycles. it might be affected by ovarian superovulation and endometrial local scratching. objective: this study aims to investigate the effect of local endometrial injury on the outcome of iui cycles. materials and methods: in this randomized clinical trial 144 women with unexplained infertility, mild male factor, and mild endometriosis randomly divided into two study groups through block randomization. the patients were randomly assigned to undergo endometrial biopsy between days 6-8 of the previous menstrual cycle before iui (n=72, iui cycles =126) or receive no interventions (n=72, iui cycles=105). results: the pregnancy rate per patient was 17 (23.6%) and 14 (19.4%) in endometrial biopsy and control groups, respectively (p=0.686). the pregnancy rate per cycle was 17/126 (13.5%) and 14/105 (13.3%) in endometrial biopsy and control groups, respectively (p=0.389). the abortion rate was comparable between the two groups (6.9% vs. 9.7%; p=0.764). the ongoing pregnancy rate was found to be comparable between the two study groups, as well (16.7% vs. 9.7%; p=0.325). endometrial thickness (p=0.609) was comparable between the groups; however er2r was significantly lower in the endometrial biopsy group (p<0.001). conclusion: application of local endometrial injury in the cycle before the iui cycles is not associated with increased pregnancy rate per patient and per cycle, decreased abortion, and increased endometrial thickness.