Abstract: Objective：To investigate the effects of sildenafil citrate on the pregnancy outcomes of frozen embryo transfer (FET) in patients after the resection of intrauterine adhesion (IUA). Methods: A total of 310 infertile patients receiving FET who were diagnosed as IUA  between January and December 2017, and resected IUA under hysteroscopy before their FET treatment, were included. The 190 cases in the control group were given the FET cycle with hormonal replacement, while the 120 patients in the test group were given the above FET cycle combined with sildenafil citrate. After the menstruation was clean, 50 mg of sildenafil citrate was administrated vaginally every day until the transplantation. Firstly, the gestational outcomes were compared between the two groups. Each group was subdivided into two subgroups: a gentle IUA subgroup and a medium-severe IUA subgroup. The gestational outcomes were then compared again. Results: The clinical pregnancy rate in the test group was significantly higher than that in the control group[50.83% (61/120) vs. 34.74% (66/190), P＜0.05]. However, there was no significant difference in the embryo implantation rate between the two groups [31.17% (72/231) vs. 21.82% (79/362), both P＞0.05]. There was no significant difference in the clinical pregnancy rate or embryo implantation rate between the two gentle IUA subgroups. However, The clinical pregnancy rate [44.78% (30/67)] and the embryo implantation rate [28.46% (37/130)] in the medium-severe IUA subgroup of the test group were significantly higher than those in the medium-severe IUA subgroup of the control group (both P＜0.05). No significant differences were found in the miscarriage rate and the ectopic pregnancy rate between the two groups (P＞0.05). Conclusions: Sildenafil citrate can improve the endometrial receptivity after IUA, and can significantly increase the pregnancy rate of FET in those medium-severe IUA patients.

Key words: Frozen embryo transfer, Cryopreservation, Embryo transfer, Intrauterine adhesion, Uterine diseases, Sildenafil citrate, Hormone replacement therapy, Pregnancy rate