Rectal fossa fluid by ultrasound indicates pelvic inflammatory disease. Pelvic inflammatory disease is due to vaginitis, cervicitis and endometrial inflammation caused by prolonged ineffective treatment of upstream infection, of course, can not be excluded from the fallopian tube inflammation caused by. And pelvic inflammation and tubal inflammation can be infected with each other. Therefore, once diagnosed, timely treatment should be carried out, so as to avoid prolonged inflammation without effective treatment, which will lead to inflammation of the fallopian tubes and ovaries.