Use of ultrasound in monitoring ovulation induction with human pituitary gonadotropins

Serial follicular growth was studied using real-time ultrasound scanning in 26 anovulatory patients in 55 cycles stimulated with exogenous human pituitary gonadotropin (hPG) and human chorionic gonadotropin (hCG). Dosage was monitored with urinary total estrogen estimations. The ultrasound findings were not made known to the attending physician. Forty-four cycles (80%) were ovulatory, and conception occurred in 13. The mean follicular diameter of 17 to 25 mm at ovulation corresponded with the range observed in spontaneous cycles, although the rate of follicular growth was faster with hPG. On the day the ovulatory dose of hCG was given, as determined by the first urinary estrogen value greater than 50 microgram/24 hours, estrogen excretion was similar whether single or multiple follicles of potential ovulatory size were present, but mean follicular diameters were significantly smaller when there was more than 1 follicle. During the last 4 days before ovulation, the mean diameters in conceptual cycles increased from 14.2 mm to 19.7 mm, values similar to those observed in spontaneous cycles, but different growth patterns occurred in some nonconceptual cycles. Ovarian hyperstimulation was identified by ultrasound scan in 4 of 5 cycles before urinary estrogen excretion exceeded the normal range. Although ultrasound scan does not supplant estrogen monitoring, it can assist in the early detection of hyperstimulation, in the more accurate timing of the ovulatory dose of hCG, and in the withholding of hCG when 3 or more ovulations are possible. It is recommended that ultrasound examination be performed in all patients before the ovulation-inducing dose of hCG is given to provide information on the number of follicles that are likely to ovulate and thus avoid conception of more than twins.