The following reasons should be ruled out clinically: 1. exclude ectopic pregnancy, which often occurs in the early stages of ectopic pregnancy when there is a history of menopause but a small amount of vaginal bleeding and then no bleeding; 2. due to a sudden emotional shock when menstruation occurs, such as a serious emotional shock or sudden cold stimulation will lead to a sudden absence of menstruation; 3. It is recommended that hot brown sugar and ginger water can be taken clinically to expel cold and warm the uterus, and can make the menstrual blood flow more smoothly. 3. Therefore, urine pregnancy test, sex hormone test and ultrasound are required.