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

Abstract

Objectives: To investigate the endometrial effects of letrozole in PCOS women with poor endometrial response (endometrium thickness ⩽7 mm) to clomiphene citrate (CC) despite adequate ovulation, using the ultrasonographic markers of endometrial receptivity. Study design: Ambidirectional cohort study. Patients and methods: Sixty women with anovulatory PCOS having endometrial thickness less than 7 mm despite adequate ovulation with CC underwent ovulation induction with Letrozole (5 mg/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. Results: 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 < 0.05), multilayered endometrial pattern (93.33% vs. 50%, respectively; P < 0.05) and rate of detection of subendometrial blood flow. Both RI and PI of spiral arteries in the letrozole cycle (0.63 ± 0.05 and 1.12 ± 0.06, respectively) showed significantly lower impedance compared to the previous CC cycle (0.75 ± 0.09 and 1.42 ± 0.13, respectively) (P < 0.05). Pregnancy rate per cycle was 20% (12/60) in the letrozole cycle, all in women with endometrial thickness ⩾7 mm. Conclusion: Letrozole is an effective second-line treatment in women with inadequate endometrial response to CC, as letrozole increased endometrial thickness trilaminar pattern and improved endometrial perfusion.

Keywords

• PCOS
• Clomiphene citrate
• Letrozole
• Thin endometrium
• Receptivity
• Doppler