Study of Endometrial and Uterine Doppler Markers when Using Letrozole and Clomiphene Citrate in Subfertile Patients with PCOS or Unexplained Subfertilit
Background: Clomiphene citrate has agonist and antagonist estrogen receptor properties with a discrepancy between pregnancy rate and ovulation rate. Letrozole works as a competitive, nonsteroidal aromatase inhibitor. Both stimulate ovarian follicles development. Methods: In this randomized prospective study, We recruit infertile Patients with PCOS or unexplained subfertility from the subfertility clinic at Al Moosa Specialist Hospital. We randomized patients to use either clomiphene or letrozole. On the day of the hCG trigger and the mid-luteal day, we recorded Endometrial thickness, pattern, blood flow, endometrial scoring system, uterine artery and sub endometrial arteries Doppler indices. Results: The mean of sub endometrial artery PI and RI on the day of the trigger was lower with the clomiphene treated patients than the letrozole treated patients with a p-value of .0003 and .0004, respectively. Endometrium pattern was more favourable in the letrozole treated patients than in the clomiphene treated patients with a p-value of 0.008 on the mid-luteal phase day. Letrozole treated patients had a better pregnancy rate. However, the evidence is not sufficient to suggest that there is a difference with a p-value of .728. Conclusions: When comparing letrozole with clomiphene citrate group, letrozole is associated with a more favourable (type A) pattern but less favourable endometrial vascularity on the mid-luteal day. While on the day of the trigger letrozole was less favourable in terms of sub endometrial impedance (higher sub endometrial PI. and RI). Letrozole treated patients has a better pregnancy rate, but the difference is not significant.