Chronic pelvic pain — typically during menstruation — is the most common indication of endometriosis, an incurable inflammatory condition that can cause infertility, an expert says. About 10% of women have the disorder in which tissue that normally lines the uterus grows outside of it and can spread to areas such as the fallopian tubes, ovaries and pelvis. “The most common symptom of endometriosis is painful periods,” said Dr. Kristin Riley, interim chief of the Division of Minimally Invasive Gynecologic Surgery at Penn State Health Milton S. Hershey Medical Center in Hershey, Pa. “We’re talking about the kind of pain that doesn’t go away with a simple treatment, like over-the-counter medications,” she said in a center news release. “Pain that keeps you from going to work or school or from participating in social activities.” Typically, the pain occurs before, during, or just after periods. But Riley said some women may only have …