Endometrial effects of letrozole and clomiphene citrate in women with polycystic ovary syndrome using spiral artery Doppler

To compare the effects of letrozole and clomiphene citrate (CC) on endometrial response in PCOS using subendometrial spiral artery Doppler. Fifty consecutive patients of anovulatory PCOS were recruited. Twenty-five patients (58 cycles) received 2.5-5 mg of letrozole; 25 patients (56 cycles) received 50-100 mg of CC (both orally on days 5-9 of menses). Main outcome measures: number of dominant follicles, endometrial thickness (ET), spiral artery resistance index (RI) and pulsatility index (PI) and pregnancy rate. The mean number of dominant follicles in letrozole group and CC groups was 1.63 +/- A 1.02 and 1.62 +/- A 0.96, respectively (P > 0.05). The mean mid cycle ET was 6.9 +/- A 0.74 mm in letrozole group and 5.9 +/- A 0.53 mm in CC group (P < 0.05). In letrozole and CC groups, the mean RI of spiral artery were 0.63 +/- A 0.05 and 0.79 +/- A 0.09, respectively, and the mean PI of spiral artery were 1.19 +/- A 0.06 and 1.55 +/- A 0.13, respectively. Both RI and PI in the letrozole group showed significant lower impedance compared to CC group (P < 0.05). Pregnancy rate per cycle was 19% (11/58) in the letrozole group and 12.5% (7/56) in the CC group (P > 0.05). The effect of letrozole showed a significantly better endometrial response compared to CC.