Pelvic inflammatory disease (PID) is an infection of the female upper genital tract including the uterus, fallopian tubes, and surrounding pelvic structures. It is usually caused by sexually transmitted pathogens like Neisseria gonorrhoeae and Chlamydia trachomatis ascending from the cervix. PID affects sexually active young women and can lead to long-term complications like tubal factor infertility if left untreated. Treatment involves antibiotics to provide broad coverage of likely pathogens. Hospital admission is recommended for severe cases or if surgical issues can't be ruled out, while mild cases may be treated with oral antibiotics.