Uterine effects of clomiphene citrate in women with polycystic ovary syndrome: a prospective controlled study

BACKGROUND: Previous data on the efficacy of clomiphene citrate, the most commonly used drug for treating anovulatory infertility in patients with polycystic ovary syndrome (PCOS), have shown a discrepancy between ovulation and pregnancy rates. In the present subanalysis (of a larger previously published randomized controlled trial), the effect of clomiphene citrate on several ultrasonographic markers of uterine receptivity in PCOS patients who ovulated under treatment was studied. METHODS: Thirty-three PCOS women who ovulated under 150 mg daily clomiphene citrate and 33 healthy controls were studied. Uterine, subendometrial and endometrial blood flows, endometrial thickness and pattern were assessed using serial ultrasonographic assessments. The data were analysed before and after grouping the clomiphene citrate-stimulated ovulatory cycles for reproductive outcome [unfavourable (ovulation alone or early pregnancy loss) or favourable outcome (clinical pregnancy and/or live birth)]. RESULTS: Both before and during treatment, uterine vascularity assessed at all sites was significantly lower in the PCOS group than in controls. Endometrial thickness and pattern were impaired in the PCOS group under clomiphene citrate treatment. A significant difference in all ultrasonographic parameters was observed between cycles ending in unfavourable versus those ended in favourable outcome. CONCLUSIONS: Clomiphene citrate administration alters several surrogate ultrasonographic parameters of uterine receptivity, and this effect could be crucial for its efficacy.