Pelvic inflammatory disease (PID) is a term used to describe any infection in the lower female reproductive tract that spreads upward to the upper female reproductive tract. The lower female genital tract consists of the vagina and the cervix. The upper female genital tract consists of the body of the uterus, the fallopian or uterine tubes, and the ovaries.

PID, also called salpingitis (inflammation of the fallopian tubes), endometritis (inflammation of the inside lining of the body of the uterus), or pelvic peritonitis (inflammation inside of the abdominal cavity surrounding the female reproductive organs), is the most common and most serious consequence of infection with sexually transmitted diseases (STDs) in women.

Over one million cases of PID are diagnosed annually in the United States, and it is the most common cause for hospitalization of reproductive-age women. Sexually active women aged 15-25 are at highest...