Isolated menses in prepubertal girls.

Seventeen prepubertal girls 1 to 8 years of age were studied for the complaint of vaginal bleeding of apparent uterine origin. The bleeding was considered as isolated menses because it lasted two to five days and no other signs of sexual development or any detectable vaginal or uterine abnormalities were found. Eleven girls had two or more apparent menstrual periods, six experienced only one period. Height and bone age were not significantly different from normal. Laparoscopy or ultrasonography showed normal prepubertal uterine size, with either prepubertal ovaries or ovaries containing follicular cysts. Plasma gonadotrophins and their response to luteinizing hormone-releasing hormone were at prepubertal levels. Plasma estradiol level was significantly above the normal prepubertal range, suggesting transient ovarian activity and instability of the pituitary-gonadal axis in these girls. Isolated menses occurred mainly during the months of September to January, thus leading us to speculate about possible seasonal variations of hormonal regulation.