Monitoring of clomiphene citrate stimulation by means of plasma 17 beta-oestradiol determinations and ultrasonographic follicle measurements in in-vitro fertilization treatment cycles.

In 57 in-vitro fertilization (IVF) cycles stimulated with clomiphene citrate the relationship between plasma 17 beta-oestradiol (E2) and ultrasonographic measurements of follicle diameter was assessed. Under both monofollicular and multifollicular conditions a wide range in plasma E2 values was observed in the late follicular phase. No significant correlation could be established between the dimensions of the dominant preovulatory follicle and plasma E2 values, in mono-follicular or multi-follicular cycles. Pregnancies and conceptions occurred in cycles with both low and high circulating E2 levels. In pregnancy cycles a slight increase in plasma E2 values was found on the day following administration of human chorionic gonadotrophin (HCG). In conceptional cycles not leading to a clinical pregnancy, plasma E2 profiles varied considerably, whereas in cycles in which no oocytes were fertilized, plateauing or a distinct decrease occurred during this particular period. The present study suggests that the relative daily increase in plasma E2 values may be the most relevant aspect of plasma E2 monitoring.