Low menstrual flow can be caused by many factors including uterine factors, ovarian factors and endocrine factors of the whole body. Ovarian factors, including ovarian hypofunction or ovarian failure, may cause decreased menstrual flow and are usually difficult to treat. In case of uterine factors, including adhesions or scarring of the uterine cavity due to multiple scrapings or abortions, further hysteroscopy is required. If the diagnosis of uterine adhesions is confirmed, estrogen and progesterone replacement therapy should be performed after separation of the uterine adhesions. In case of endocrine factors, such as hyperthyroidism, hypothyroidism or pituitary tumor, the menstrual flow will slowly increase after the treatment of the original disease.