Pelvic inflammatory disease (often abbreviated as PID) is a result of untreated infections, most commonly chlamydia and gonorrhea. It most commonly appears as an infection of the fallopian tubes (salpingitis) or the lining of the uterus (endometritis) and can cause extensive pelvic scarring. It can lead to such complications as infertility, higher risk of ectopic (tubal) pregnancy and chronic pelvic pain.