Prevalence and genesis of endometriosis.

A group of 1542 pre-menopausal Caucasian women were assessed prospectively to investigate the prevalence of endometriosis. The women were either having laparoscopy because of infertility (n = 654), undergoing laparoscopic sterilization (n = 598), having laparoscopy because of chronic abdominal and pelvic pain (n = 156) or undergoing abdominal hysterectomy for dysfunctional uterine bleeding (n = 134). Endometriosis was noted more frequently among women being investigated for infertility (21%) than among those undergoing sterilization (6%). Among those being investigated for chronic abdominal pain, the incidence of endometriosis was 15%, while among those undergoing abdominal hysterectomy, it was 25%. In all groups the total duration of combined pill usage was significantly higher in patients who had a normal pelvis compared to those with endometriosis. It is suggested that among susceptible women, both fertile and infertile, a prolonged period of regular spontaneous menstruation may play a causative role in the genesis of endometriosis.