A randomized clinical trial of sildenafil plus clomiphene citrate to improve the success rate of ovulation induction in patients with unexplained infertility.

To investigate the role of sildenafil citrate in improving ovulation induction success rate in women with unexplained infertility.A randomized clinical trial from January to December 2018 of 80 women with unexplained infertility randomized into two groups. Both groups received 100 mg clomiphene citrate once daily from days 3-7 of the menstrual cycle. The study group also received 25 mg oral sildenafil citrate twice daily from days 8-12 of the same cycle. Transvaginal ultrasound assessed ovulation, endometrial thickness, and number of follicles. Pregnancy was assessed 2 weeks after ovulation. Primary outcome measures were endometrial thickness, number of mature follicles, and pregnancy rates.Pregnancy rates (26 (65%) and 16 (40%), P=0.043) and endometrial thickness (10.4±1.4 and 9.2±1.9, P=0.007) were significantly higher in the study group. More women in the study group reported adverse effects compared with the control group (17 [42.5%] vs 9 [22.5%]; P=0.034), with headache the most common adverse effect in the study group, reported by 8 (20.0%) patients.Adding sildenafil citrate improved ovulation success rate and increased pregnancy rate.