Endometriosis: pathogenetic implications of the anatomic distribution

The authors have reassessed the anatomic distribution of ectopic endometrium by the laparoscopic study of the location of implants, adhesions, and uterine position in 182 consecutive patients with infertility and endometriosis. The ovary was the most common site of implants with 54.9% having either unilateral or bilateral involvement. This was followed, in order of frequency, by the posterior broad ligament (35.2%), the anterior cul-de-sac (34.6%), the posterior cul-de-sac (34.0%), and the uterosacral ligament (28.0%). Adhesion formation followed the same anatomic distribution. No patients were noted to have endometriosis of the cervix and vagina. Endometriosis of the anterior compartment (anterior cul-de-sac, anterior broad ligament, and anterior uterine serosa) was significantly more common in patients with anterior uteri (40.7%) versus patients with posterior uteri (11.8%, P less than .0005). Exclusive anterior compartment disease was found only in patients with anterior uteri, and significantly more commonly in patients with severely anteflexed uteri (P less than .005). These data suggest that factors influencing implantation of retrograde menstrual debris include: the dependent pooling of peritoneal fluid as affected by uterine position; epithelial cell type at the site of implantation; unique ovarian susceptibility; route of entry; and mobility of the pelvic structures. The data support the Sampson hypothesis of retrograde menstruation as the primary model of development of endometriosis.