The diagnosis of “pelvic effusion” is often found in ultrasound results. Some patients may be distressed by this. It is very important to correctly interpret “pelvic fluid” in ultrasound results. Pelvic fluid can be divided into physiological pelvic fluid and pathological pelvic fluid. Physiological pelvic effusion is because the pelvic cavity is the lowest part of the abdominal cavity in the whole body, when there is exudate or leakage, it will drain into the pelvic cavity, thus becoming pelvic effusion. “Some normal women may have pelvic effusion in the ultrasound results during menstruation or ovulation, but “patients” do not have any symptoms. Patients with pathological pelvic fluid, on the other hand, should go to the hospital in a timely manner and receive evidence-based treatment.