Hormonal and ultrasonic characteristics of 23 clomiphene citrate stimulated cycles resulting in pregnancies after in vitro fertilization and embryo transfer.

In vitro fertilization (IVF) and embryo transfer (ET) were successful in 24 clomiphene citrate stimulated cycles in 22 patients. Ovarian follicular growth was monitored by ultrasound (US) and serum estradiol (E2) concentrations in order to determine the most favorable time for the induction of ovulation by administration of human chorionic gonadotropin (hCG). The day of the hCG injection was considered day 0. After an almost linear growth the mean diameter of the dominant follicle reached 19.3 +/- 2 mm on day 0. Serum E2 concentrations also increased in almost linear fashion up to a maximum of 1,037 +/- 322 pg/ml on day +1. On day 0 the mean serum E2 concentration was 862 +/- 279 pg/ml. A mean serum E2 concentration per dominant and codominant follicle of 328 +/- 100 pg/ml was found on day 0. There was no linear correlation between the follicular diameters and the serum E2-values on the same day. The time of ovum recovery was often different to the time at which ovulation would have been expected in a normal cycle.