Assessment of ovulation by ultrasound and plasma estradiol determinations

The timing of ovulation was studied daily during the periovular period in 19 women attending an artificial insemination clinic during 24 menstrual cycles; B-mode ultrasound examination and plasma estradiol (E2) determinations were used. The maximum diameters of the ovarian follicles and the peak plasma E2 determinations all occurred within 2 days prior to and including the day of ovulation, as determined by conventional means, in the 12 normal cycles studied. The average values on the day prior to ovulation (day -1) for maximum follicle size and peak E2 determination were 2.5 cm and 1660 pmole/liter, respectively. Two definite ultrasonic patterns were noted after ovulation: The follicle either disappeared or filled with internal echoes. It is concluded from the preliminary study that ultrasound examination and plasma E2 determinations are equally effective in predicting the time of ovulation.