If it's caught and treated early, pelvic inflammatory disease (PID) generally doesn't cause any complications. However, if left untreated, it may cause serious complications. The infection may cause scarring in the fallopian tubes, which can lead to infertility. In fact, a third of the women who get PID will become infertile. Scar tissue may also increase the chances of ectopic pregnancy, which is a serious condition in which the fertilized egg can't travel into the uterus and becomes stuck in the fallopian tubes. In some cases, PID may lead to chronic pelvic pain that can last for years. To prevent these potential complications, talk to your doctor right away if you notice any symptoms that may be caused by PID.