Ultrasound monitoring of ovarian follicular growth during spontaneous cycles in Nigerian women.

Thirty-nine spontaneous cycles in 34 women (22 patients from the infertility clinic and 12 normal volunteers) were serially studied by ultrasound to monitor follicular growth for ovulation prediction and detection. Ovulation was also confirmed by a mid-luteal phase progesterone assay using WHO match RIA kits. Ovulation occurred from the left ovary in 21 cycles (54%) and from the right ovary in 18 cycles (46%). The maximum follicular diameter prior to ovulation was 21.0 +/- 3.48mm with a range of 15-28 mm. The maximum pre-ovulatory size in the group of infertile patients 21.4mm (range 15-28 mm) was not statistically different from the size in normal volunteers 20.8mm (range 15.5-27mm) (P > 0.05). Bilateral ovulation occurred in two patients. Changes in shape and/or size of the follicle mostly associated with increased internal echoes were the indices of ovulation in 84.7% of cases. Follicular diameter of 15mm may indicate imminent ovulation in Nigerian women. Infertility management procedures such as artificial insemination, timed sexual intercourse may commence just before or once this follicular size has been attained until ovulation is detected.