Endometriosis and pelvic pain: epidemiological evidence of the relationship and implications

The relationship between chronic pelvic pain symptoms and endometriosis is unclear because painful symptoms are frequent in women without this pathology, and because asymptomatic forms of endometriosis exist. Our comprehensive review attempts to clarify the links between the characteristics of lesions and the semiology of chronic pelvic pain symptoms. Based on randomized trials against placebo, endometriosis appears to be responsible for chronic pelvic pain symptoms in more than half of confirmed cases. A causal association between severe dysmenorrhoea and endometriosis is very probable. This association is independent of the macroscopic type of the lesions or their anatomical locations and may be related to recurrent cyclic micro-bleeding in the implants. Endometriosis-related adhesions may also cause severe dysmenorrhoea. There are histological and physiopathological arguments for the responsibility of deeply infiltrating endometriosis (DIE) in severe chronic pelvic pain symptoms. DIE-related pain may be in relation with compression or infiltration of nerves in the sub-peritoneal pelvic space by the implants. The painful symptoms caused by DIE present particular characteristics, being specific to involvement of precise anatomical locations (severe deep dyspareunia, painful defecation) or organs (functional urinary tract signs, bowel signs). They can thus be described as location indicating pain. A precise semiological analysis of the chronic pelvic pain symptoms characteristics is useful for the diagnosis and therapeutic management of endometriosis in a context of pain.