Human Reproduction Page 1 of 7 doi:10.1093/humrep/del079 Deeply infiltrating endometriosis: pathogenetic implications of the anatomical distribution

BACKGROUND: To investigate whether knowledge of the anatomical distribution of histologically proven deeply infiltrating endometriosis (DIE) lesions contributes to understanding the pathogenesis. METHODS: Observational study between June 1992 and December 2004 (retrospective study between 1992 and 2000; prospective study between 2001 and 2004). Continuous series of 426 patients suffering from pelvic pain who underwent complete surgical exer-esis of DIE. DIE lesions were classified according to four different possibilities: (i) Firstly, DIE lesions were classified as located in the anterior or posterior pelvic compartment. (ii) Secondly, DIE were classified as left, median and right. (iii) Thirdly, DIE lesions were classified as pelvic or abdominal. (iv) Fourthly, DIE lesions that could present in a right and/or left location were classified as unilateral or bilateral. RESULTS: These 426 patients presented 759 histo-logically proven DIE lesions: bladder (48 lesions; 6.3%); uterosacral (USL) (400 lesions; 52.7%); vagina (123 lesions; 16.2%); ureter (16 lesions; 2.1%) and intestine (172, 22.7%). DIE lesions are significantly more often located in the pelvis (n = 730 lesions) than in the abdomen (n = 29 lesions) (P < 0.0001). Pelvic DIE lesions are significantly more often