Pelvic inflammatory disease (PID) is an infection of the female upper genital tract that can cause long-term complications if not treated promptly. It is usually caused by bacteria spreading from the vagina or cervix, such as Chlamydia trachomatis and Neisseria gonorrhoeae. Left untreated, PID can lead to infertility, ectopic pregnancy, chronic pelvic pain, and increased risk of HIV transmission. Treatment involves a combination of antibiotics to cover common causative organisms, with hospitalization recommended for severe cases. Prompt treatment is important to prevent long-term complications.