The role of ultrasound in ovulation induction: a critical appraisal.

Twenty-five cycles induced by human menopausal gonadotropin (hMG) were serially studied by ultrasound. The developing follicles were observed up to and beyond human chorionic gonadotropin (hCG) administration. Ovulation as determined by subsequent pregnancy or a sustained elevation of basal temperature was seen in 18 of these cycles. Among these patients the follicular size ranged between 24 and 13 millimeters. No pregnancies occurred where the follicular size was below 15 mm. A shortened luteal phase was noted in three cycles where the follicular size was either 13 or 14 mm. Multiple follicles greater than 10 mm were observed in 14 of the ovulating cycles, but in no case did a multiple pregnancy occur. Fifteen millimeters is therefore suggested as a minimum size for satisfactory ovulation, but it does not appear that an optimum size exists. We conclude that ultrasound can play an important role in the monitoring of ovulation induction but does not replace the present methods.