Impact of letrozole on ultrasonographic markers of endometrial receptivity in polycystic ovary syndrome women with poor endometrial response to clomiphene citrate despite adequate ovulation

To investigate the endometrial effects of letrozole in PCOS women with poor endometrial response (endometrium thickness ⩽7mm) to clomiphene citrate (CC) despite adequate ovulation, using the ultrasonographic markers of endometrial receptivity. Ambidirectional cohort study. Sixty women with anovulatory PCOS having endometrial thickness less than 7mm despite adequate ovulation with CC underwent ovulation induction with Letrozole (5mg/day from cycle day 3 to 7) for one treatment cycle. Main outcome measures: Comparison of the endometrial thickness (ET) and pattern, uterine artery and spiral artery, resistance index (RI) and pulsatility index (PI) between the current letrozole and previous CC stimulated cycles. In the current letrozole cycle compared with the previous CC cycles, there were significantly greater midcycle endometrial thickness (8.97±1.32 vs. 5.7±1.2, respectively; P