Effects of hysterosalpingo-contrast sonography examination on endometrial receptivity among women with unexplained infertility

Purpose: Hysterosalpingo-contrast sonography (HyCoSy) is the preferred method for evaluating fallopian tubal patency, and it is associated with improved rates of natural pregnancy among infertile patients. However, the mechanism underlying the improvement in pregnancy rates following HyCoSy remains unclear. This study aimed to investigate the effect of HyCoSy examination on endometrial receptivity as well as pregnancy rates among infertile women. Methods: This prospective study included 120 women with unexplained infertility who visited our department between June 2018 and February 2021. These patients were classified into the study group (n = 60) and the control group (n = 60) depending on their willingness to undergo three-dimensional HyCoSy in the present cycle (study group) or 6 months later (control group). Endometrial characteristics, including endometrial thickness and pattern as well as the endometrial blood flow distribution pattern, were measured twice by transvaginal Doppler ultrasonography in the preovulatory phase before and after HyCoSy examination. Participants were followed for 6 months to observe the outcome of spontaneous conception. Results: Compared with the control group, the study group had a significantly higher cumulative pregnancy rate at 6 months after HyCoSy (21.6% [13/60] vs 5.0% [3/60], P = 0.007). More patients in the study group showed improved endometrial blood flow distribution (P = 0.021, χ = 7.699), but no differences in endometrial thickness and pattern were observed between the groups (P > 0.05). Conclusion: HyCoSy examination may improve endometrial perfusion and has a therapeutic effect on improving spontaneous pregnancy among women with unexplained infertility.