Left:right side ratio of endometriotic implants in the pelvis

Objective: The frequency of endometriotic lesions in the right and left hemipelvis was analysed in 856 women with endometriosis. Eligible for the study were women with primary or secondary sterility, chronic pelvic pain, fibroids or benign ovarian cysts requiring laparoscopy or laparotomy consecutively observed between May 1991 and July 1992 in 23 obstetric and gynecology departments in Italy. Women with a previous diagnosis of endometriosis were excluded. A total of 3684 women entered the study. Of those, 856 had endometriosis and are considered in the present analysis. Results: Five hundred and ninety four had bilateral lesions (including both ovarian and peritoneal lesions). Of the 262 women with unilateral lesions, 118 (45%, 95% confidence intervals (CI) 38–54) had the lesions in the right side of the pelvis and 144 (55%) in the left one. Conclusions: From an anatomical point of view, these findings support the transplantation therapy in the pathogenesis of endometriosis.