The effect of administering vaginal estrogen to clomiphene citrate stimulated cycles on endometrial thickness and pregnancy rates in unexplained infertility

Objective: Clomiphene citrate (CC) has some negative effects on the endometrium. We aimed to determine the effect of vaginally administered local estrogen (LE) on endometrial thickness (ET) and pregnancy rates in CC stimulated cycles. Material and Methods: This was a prospective randomized crossover study that took place in a university hospital. The patients had received CC due to unexplained infertility (UI). Two different treatment protocols were given sequentially as, either CC+LE or CC alone. Each protocol was planned for two cycles and there was a one-month wash-out period between protocols. The effects of LE on the 3rd and 9th day, the ovulation day (OD) and 7th postovulation day (POD7) were investigated Results: A total of 6 pregnancies were achieved with 3 patients from each protocol. The ET was 7.6±1.4 mm and 8.3±2.1 mm respectively and significantly different in the CC group and the CC+E2 groups on the OD (p=.039), while these values were 9.7±2.3 mm and 10.9±3.0 mm respectively and significantly different on the POD7 (p=.007). There was no significant difference between the groups for arterial PI values on the OD and POD7. The frequency of thin endometrium (<6 mm) was 15.2% and 12.2% respectively in the CC group and the CC+E2 group on the OD (p=.628) and 5.1% and 1.2% respectively on the POD7 (p=.182).Conclusion: Adding vaginal LE to CC stimulated cycles led to a significant increase in ET on the OD and POD7. However, this difference in thickness was not reflected in the pregnancy rates in this study.