It was observed that embryos from oocytes resulting from well-vascularized follicles had a higher implantation rate than those from oocytes developed in poorly vascularized follicles. Neovascularization was recognized as primary in terms of ovulatory follicles growth and selection. Vascular endothelial growth factor serum level has a positive correlation with perifollicular blood flow. The 2D Color and Pulsed Doppler ultrasounds that allow visual observation of the flux of the blood in a limited part of the wall of the preovulatory follicles can be easily measured. To study the preovulatory follicle's blood flow parameters in infertile women undergoing different ovulation induction protocols. 50 infertile female patients who had undergone Intrauterine Insemination (IUI) procedures were classified into two groups which were letrozole or clomiphene citrate groups as induction protocol. Another ultrasound was performed on cycle day 11, 12, or 13 to evaluate growth follicles, also a Doppler study was done to measure perifollicular blood flow and endometrial thickness at the same time blood sample to measure vascular endothelial growth factor were taken. Human chorionic gonadotropin was injected and then after 36-40 hrs. IUI Procedure is done and follows up with the patient to do a pregnancy test after 14 days. The number of dominant follicles, endometrial thickness at HCG trigger, Perifollicular doppler blood flow vascular endothelial growth factor level, pregnancy rates were all measured in both groups. There were significant differences in Perifollicular RI (p<0.001) but there were no significant differences in Perifollicular PI (p=0.476). Regarding pregnancy rate, the letrozole group has a higher although not significant pregnancy rate (32%), if compared with those using CC (20%).
E ndometrial thickness (ET) is one of the best predictors of implantation rate and pregnancy success rate because endometrial growth depends on hormones. Estrogen regulates the proliferative phase, endometrial proliferation induced by estrogen after menstruation is largely dependent on blood flow to the basal endometrium that produces progesterone receptors which are required for progesterone-regulated endometrial growth in the secretory process. To compare the effect of estradiol valerate vs. sildenafil citrate on endometrial receptivity and subsequent pregnancy outcome in unexplained infertility patients receiving letrozole for ovulation induction. Herein, 21 patients with unexplained infertility underwent ovulation induction by letrozole (2.5 mg). Patients were divided into 2 groups; group A (10 patients) were given sildenafil tablets vaginally (25 mg) four times daily and group B (11 patients) were treated with estradiol valerate tablet 2 mg/12 hours. Patients were evaluated by transvaginal ultrasonography (TVS) to determine endometrial thickness, pattern, size, and the number of the dominant follicles, serum assessment of Vascular Endothelial Growth Factor (VEGF) level at trigger day, and chemical pregnancy outcome 14 days later. Results showed that the endometrial thickness, patterns of the endometrium, VEGF, size of the dominant follicle at the trigger day, and pregnancy rates were not significantly different between the two groups. However, the difference in the number of the dominant follicles at trigger day was statistically significant which is more in the sildenafil treated group. The present study confirmed the findings of both Sildenafil and E 2 valerate to boost endometrial receptivity and pregnancy rate.