Monitoring ovarian follicular development with real-time ultrasound.

Ovarian follicular growth during the periovulatory period was measured using real-time ultrasound in 33 patients during 53 spontaneous ovulatory cycles. The mean follicular diameter increased from 14.1 mm four days before ovulation to a maximum of 20.1 mm on the day of presumptive ovulation. The results correspond with previous static ultrasound studies of follicular development and in nine cycles in which both methods were employed the correlation between measurements on the same day was highly significant (r = 0.944; p < 0.001). The day of ovulation could not be anticipated from a single measurement because of the relatively wide range of follicular size. Except in some obese subjects, real-time ultrasound examination of the developing follicle appears to be a useful technique for assessing the progress of the ovarian cycle.