Ultrasound timing of human chorionic gonadotropin administration in clomiphene-stimulated cycle

Seventeen patients treated with clomiphene citrate were examined using real-time ultrasound timing 28 ovulatory cycles to determine the pattern of follicular development under clomiphene stimulation. The rate of growth was faster, but the follicular diameter range at ovulation was similar to that during spontaneous cycles. This information was used to time midcycle human chorionic gonadotropin (hCG) administration in over 97 cycles in 21 patients responsive to clomiphene who had not conceived. When hCG was given when the mean follicular diameter reached 18 mm, 92% of these cycles were ovulatory. Fourteen patients (67%) conceived within 6 ovulatory treatment cycles. Five of 7 patients (71%) who did not conceive were found to have endometriosis at laparoscopy. Midcycle cervical scores were significantly lower in clomiphene-treated as compared with spontaneous ovulatory cycles, and additional treatment with ethinyl estradiol did not effect a significant improvement. Timing of midcycle hCG using ultrasound is an effective method of inducing ovulation in patients in whom an estrogenic follicular response without ovulation is obtained with clomiphene treatment.