Letrozole and Clomiphene Citrate Effect on Endometrial and Subendometrial Vascularity in Treating Infertility in Women with Polycystic Ovary Syndrome

Abstract

Objective: Letrozole appears not to have any of the adverse effects on the endometrium that are frequently associated with clomiphene citrate (CC) during ovulation induction. The aim of the study is to compare the effect of letrozole compared to CC on endometrial thickness and endometrial and subendometrial blood flow. Materials and methods: Infertile women with polycystic ovary syndrome (PCOS) were allocated for ovulation induction; 102 women were treated with Letrozole and 99 women with CC. Thirty-five patients from the CC group showed a resistance to or failure of CC with a thin endometrium, and were re-treated with letrozole. The main outcome measures were ovulation and pregnancy rates/cycle, endometrial thickness, detection rates, and resistance index (RI) and pulsatility index (PI) of subendometrial and endometrial blood flow. Results: In spite of a nonsignificant difference in ovulation rate between letrozole and CC groups (70.6% vs. 64.6%), a clinical pregnancy rate was achieved in 29/102 (28.4%) women with letrozole and 20/99 (20.2%) women with CC treatment (p<0.05) and in 6/35 (17.1%) in women re-treated with letrozole after CC resistance or failure. There were significant differences in endometrial thickness, detection rates, and RI and PI of subendometrial and endometrial blood flow between the two groups and between 35 women re-treated with letrozole after CC resistance or failure when compared with CC treatment alone. Conclusions: Letrozole may increase fertility by improving endometrial receptivity compared with CC alone. (J GYNECOL SURG 28:405)