ABSTRACT
BACKGROUND: Both sildenafil and estradiol are seen to improve endometrial thickness in patients with infertility who are undergoing clomiphene induction cycles. However, the correlation between endometrial thickness and pregnancy rate is debatable. This study investigated the effect of adding oral sildenafil to clomiphene citrate (CC), compared to adding estradiol valerate, on the uterine biophysical profile (Applebaum score) and pregnancy rate. METHODS: This was a double-blinded, randomized controlled trial conducted in Kisangani in the Democratic Republic of the Congo from October 1, 2021, to October 31, 2023. Patients with unexplained infertility were randomly assigned to one of two groups: the interventional, which was given CC (2 x 50 mg/day from day 3 to day 7 of the menstrual cycle) + sildenafil (2 x 25 mg/day orally from day 8 to day 12) or (ii) the control group, which was given CC (similar dosage as the intervention group) + EV (2 x 2 mg/day orally from day 8 to day 12), for a maximum of three cycles. Applebaum scores and clinical pregnancy rates were measured. RESULTS: Patients in the sildenafil and EV groups were similar in mean age (29.04 versus 28.89 years). Of the 74 patients enrolled in each group, 71 in the sildenafil group and 72 in the EV group received treatment and were followed to completion. The Applebaum scores were significantly higher in the sildenafil group than in the EV group (17.05 versus 15.14, respectively, P=0.000). In the sildenafil group, the clinical pregnancy rate was also significantly higher, at 28.92% versus 20.83% in the EV group (P = 0.04). CONCLUSION: As compared to EV, the oral addition of sildenafil to CC is associated with a good Applebaum score and a high rate of clinical pregnancy in patients with unexplained infertility.