Chronic pelvic pain can be caused by scar tissue that develops following surgery, overfilling of the veins in the pelvis, referred pain from another part of the body. It can also be caused by fibroids, also known as benign tumors of the uterus. Conditions such as endometriosis, irritable bowel syndrome, chronic prostatitis, and interstitial cystitis, also known as inflammation of the bladder wall, may also result in chronic pelvic pain. It is important to remember that the underlying cause of pelvic pain cannot always be determined.