Pelvic effusion does not necessarily mean inflammation. Pelvic effusion is divided into physiological pelvic effusion and pathological pelvic effusion. Physiological pelvic effusion is due to the fact that the pelvic cavity is the lowest part of the abdominal cavity anatomically during menstruation or ovulation. When there is a small amount of exudate, leakage and ruptured bleeding from the pelvic organs, fluid first accumulates in the pelvic cavity, thus forming pelvic effusion. Pathological pelvic effusion can occur after adnexitis, pelvic inflammatory disease and endometriosis, and is the main symptom of pelvic inflammatory disease, so pathological pelvic effusion is a manifestation of inflammation and needs to be treated actively.