Chronic pelvic pain in women can be caused by various pathologies, such as endometriosis, fibroids, and adhesions. Surgical treatment of the pathology often relieves the pain, but a significant number of women continue to have pain, even after visibly successful surgery. One model explored in this study is that in some cases of chronic pelvic pain, the central nervous system has changed in its processing of pain-related signals, requiring a therapy directed to the CNS to effectively treat the pain. This model has been supported in studies of other chronic pain conditions, such as fibromyalgia and migraine. This study will seek to determine whether the analgesic effectiveness of duloxetine is related to the pain state of the individual.