. This study aimed to determine and compare the effect of vaginal sildenafil citrate and estradiol valerate on endometrial thickness, blood flow and pregnancy rates in infertile women.

The study is a randomized controlled trial that was carried on 148 infertile women with unexplained infertility. Patients were divided into 3 groups. Group 1 included 48 patients who received oral estradiol valerate (Cyclo-Progynova 2mg, from day 8th till triggering of ovulation), another 50 patients in group 2 received oral Sildenafil (Respatio 20mg/12hr film coated tablets for 5 days starting from last day of menstruation till ovulation), while group 3 was the control one who included 50 patients were given ovulation induction with CC 50mg/12hr from 2nd to 7th day of cycle. Every patient underwent a transvaginal ultrasound to determine ovulation, number of follicles, and pregnancy rates. Miscarriage, ectopic pregnancy, and multiple pregnancies were tracked for 3 months, as were any adverse consequences.

Inclusion Criteria:

• aged between 18 to 40 years
• unexplained infertility (primary or secondary)
• had a regular menstrual cycle;
• patent tubes;
• husbands with normal semen parameters.

Exclusion Criteria:

• hypotension;
• cardiovascular, hepatic, and renal diseases;
• uncontrolled diabetes mellitus;
• anovulatory infertility;
• ovarian cysts;
• pelvic adhesions;
• hyperprolactinemia;
• abnormal thyroid functions;
• multiple uterine fibroids;
• patients on nitrates;
• suspicion of endometriosis and adenomyosis,
• subjects have known to receive any treatment for fertility in the last six months