Bacterial vaginitis can lead to pelvic inflammatory disease. Bacterial vaginosis is a mixed infection caused by the imbalance of normal vaginal flora. When bacterial vaginosis occurs, the predominance of lactobacilli in the vagina decreases, leading to the overgrowth of other microorganisms such as Gardnerella, anaerobes, and some staphylococci. The proliferation of these pathogens can compromise the host's defense mechanisms. These pathogens can travel from the vagina to the uterine cavity and then to the pelvic cavity, leading to disturbances in the microecological environment of the pelvis and resulting in pelvic inflammatory disease.