If the period is 20 days early, it is not a period, but an abnormal vaginal bleeding. This condition is commonly caused by the following reasons: first, due to endocrine disorders. When the estrogen and progesterone in the body both drop, the endometrium loses the support of estrogen and progesterone, and retreating bleeding occurs, which leads to irregular vaginal bleeding in clinical practice. Secondly, irregular vaginal bleeding due to submucosal fibroids with heavy bleeding is recommended for ultrasound examination. Thirdly, irregular vaginal bleeding can be caused by inflammation of the endometrium or polyps of the endometrium. In case of pelvic tumor or other organic lesions, this may cause this condition. Therefore, the following tests are recommended: routine blood tests, vaginal ultrasound, cervical cancer screening if necessary, and then treatment according to the results clinically.