[Parameters of ovulation in spontaneous ovulatory cycles]

The parameters of ovulation used at the infertility clinic of Tygerberg Hospital were evaluated in 45 spontaneously ovulating women. The mean maximum preovulatory serum oestradiol level was 1 274 pmol/l with a standard deviation of 432 pmol/l and an average daily increase of 245 pmol/l over the last 3 preovulatory days. Normal values were identified for a cervical mucus scoring system similar to the Insler system. The mean midluteal serum progesterone value was 25,5 nmol/l with a standard deviation of 7,5 nmol/l. Ultrasound examinations of the ovaries to diagnose ovulation were used for the first time in Tygerberg Hospital; the average of maximum diameters in three dimensions was used to measure follicles. The average daily pre-ovulatory growth rate was 2,3 mm and the maximum follicle size 20,5 mm with a standard deviation of 2,3 mm. The most common ultrasonic signs of ovulation were reduction in follicle size, development of irregular borders and intrafollicular echoes. In 5 patients endometrial histological dating lagged more than 2 days behind ultrasonic signs of ovulation. These were considered cases of luteal phase insufficiency. The maximum pre-ovulatory serum oestradiol levels were statistically significantly lower in these cases.