Menstruation is defined as menstruation, and it is usually abnormal for menstruation to come 20 days early. The average woman’s menstrual cycle is 21-35 days, and it is normal for menstruation to occur a week early or late. But getting your period 20 days early is not normal. Menstruation 20 days early is usually not menstruation, but the uterus abnormal bleeding and other conditions caused by this situation may be related to endometritis, cervical polyps, cervicitis and other diseases. In addition, if a woman takes emergency contraceptive pills, resulting in vaginal withdrawal bleeding reaction, the situation does not belong to the early menstruation, the patient generally do not need to do any treatment. Clinical patients with symptoms of early menstruation 20 days, it is recommended to go to a regular hospital for timely examination and standardized treatment according to the cause of the disease.