Pelvic inflammatory disease (PID) is an infection of the upper female genital tract that is usually caused by bacteria spreading from the vagina and cervix. It is characterized by inflammation of the uterus, fallopian tubes, ovaries, and surrounding pelvic structures. Common symptoms include lower abdominal and pelvic pain, fever, abnormal vaginal discharge, and dyspareunia. Diagnosis is based on clinical criteria including cervical motion tenderness and adnexal tenderness. Treatment involves antibiotics, with hospitalization required if the infection is severe. Complications can include infertility, ectopic pregnancy, chronic pelvic pain, and recurrent infection if proper treatment and prevention measures are not followed.