The potential cavity of the normal uterine cavity is not empty and permanently propped open, but rather the anterior and posterior walls are adjoined. With fluid accumulation in the uterine cavity, the cavity between the anterior and posterior walls of the uterus gradually separates and fills with fluid structures. Therefore, uterine effusion is seen on ultrasound as a separation of the uterine cavity and the uterine cavity is filled with narrow band-like echogenic areas, which will be reported on ultrasound as uterine effusion. Uterine effusion can be caused by a variety of reasons and the final diagnosis needs to be given based on the specific condition combined with the gynecologist’s physical examination and personal medical history. In older adults, especially after menopause, a very small amount of narrow band-like anechoic areas in the uterine cavity can be considered normal. limited anechoic areas in the uterine cavity under ultrasound can be diagnosed by the ultrasonographer and prompt the clinician for further investigations.