Is endometriosis really associated with pain?

To address the contrasting findings regarding how pain is related to endometriosis, the relationship between pain and stage of endometriosis was dissected differently by the chief complaint to eliminate selection biases. A total of 1,092 women with endometriosis were classified into two groups depending on their chief complaint, i.e., infertility (infertility group; n = 476) or pain (pain group; n = 616). The correlations between disease stage and various types of pain were analyzed differently in each group. The frequencies of chronic pelvic pain and dyspareunia increased with disease stage either in the infertility group, in the pain group or in the aggregate. On the other hand, no significant relation between the severity of dysmenorrhea and disease stage was observed in the aggregate. Interestingly, a parallel increase in the severity of dysmenorrhea with disease stage was observed in the infertility group, but not in the pain group. In view of selection biases involved in analyzing endometriosis associated with pain, these results could be seen to support the contention that chronic pelvic pain, dyspareunia and dysmenorrhea are in fact related to the extent of endometriosis.