BACKGROUNDEndometriosis is a controversial and enigmatic disease. Deep infiltrating endometriosis (DIE) is responsible for painful symptoms and is the least understood type of endometriosis. Little work has been devoted to define the location of DIE lesions and its relationships with pain. The aim of the study was to investigate the relationship between the anatomical distribution of DIE lesions and pain symptoms.

METHODSClinical data from 354 patients between May 2003 and December 2007 with laparoscopically diagnosed endometriosis were collected including 177 DIE patients and 177 non-DIE patients. The pain symptoms, including dysmenorrhea (DM), chronic pelvic pain (CPP, defined as intermittent or permanent pelvic pain, not related to the menstruation and longer than 6 months), deep dyspareunia (pelvic pain at intercourse) and dyschezia (pelvic pain with defecation), were recorded for every patient before operation. Endometriotic lesions were recorded by their anatomical distributions, the depth of infiltration and lesion colors. And the relationship between the anatomical distribution of DIE lesions and pain symptoms was analyzed. Pearson's chi-square test or Fisher's exact test, one-way analysis of variance (ANOVA) and linear regression and binary Logistic regression were used for statistical analysis.

RESULTSThe duration ((13.79 ± 3.94) years) of pain suffering in DIE patients was much longer than that of non-DIE patients (P < 0.01). In DIE patients, 60.7% of the uterosacral ligament (USL) nodules were bilateral (P < 0.01); 44.6% of the cul-de-sacs were completely blocked. Rectum invasion was observed in 19.9% of DIE patients (P = 0.03); pelvic adhesion was also more common. Up to 98.41% of the deep infiltrative lesions were located in the posterior pelvic compartment. DIE lesions were also found in bladder (1.58%), USL (67.08%), cul-de-sac (12.02%), recto-vaginal septum (12.66%), rectum and rectosigmoid junction (2.85%) and ureter (3.80%). The odds ratio of USL-DIE for CPP, deep dyspareunia, dyschezia were 2.52, 1.29 and 2.24 respectively. And the depth of infiltration correlated with the severity of dysmenorrhea.

CONCLUSIONSDIE lesions were associated with severe pain symptoms. The main distribution of DIE lesions was in the posterior pelvic compartment, and was more widespread and severe in DIE patients. Moreover, resection of these DIE lesions are very important to treat the pain symptoms.