An endometrial thickness between 8-12 mm is considered normal when menstruating. If the endometrial thickness is within this range, the menstrual flow will usually be within the normal range. If the endometrium is too thin it can lead to a low menstrual flow or an unusually long menstrual period, usually related to inflammation of the endometrium, endometrial defects and uterine cavity manipulation. If the endometrium is too thick it can also have an effect on the menstrual flow, leading to increased menstrual flow with blood clots and even to hemorrhage, leading to hemorrhagic shock, functional uterine blood loss, etc. In addition, if the thickness of the endometrium is significantly abnormal, it is also necessary to consider whether there is a malignant lesion of the endometrium. Therefore, in case of abnormal menstruation, ultrasound should be reviewed and further treatment and management should be carried out according to the condition of the endometrium and the clinical symptoms of the patient.