Endometriosis and mechanisms of pelvic pain.

Endometriosis remains an enigmatic disorder in that the cause, the natural history, and the precise mechanisms by which it causes pain are not completely understood. The pain symptoms most commonly attributed to endometriosis are dysmenorrhea, dyspareunia, and chronic pelvic pain. Pain may be due to nociceptive, inflammatory, or neuropathic mechanisms, and there is evidence that all 3 of these mechanisms are relevant to endometriosis-associated pelvic pain. It is proposed that the clinically observed inconsistencies of the relationships of endometriosis severity and the presence or severity of pain are likely due to variable roles of different pain mechanisms in endometriosis. A better understanding of the roles of nociceptive, inflammatory, and neuropathic pain in endometriosis is likely to improve the treatment of women with endometriosis-associated pelvic pain.