If there is still brown discharge on the eighth day of menstruation, it is often caused by the following reasons: 1, insufficient estrogen, which is a kind of endocrine disorder, when estrogen is insufficient, the endometrium is not able to repair as soon as possible under the action of estrogen, so there will be a prolonged menstruation. 2, there is chronic inflammation in the endometrium, at this time, there is not only brown discharge on the eighth day of menstruation, often 3, there are corresponding lesions in the endometrium, such as endometrial cancer, endometrial atypical hyperplasia, and endometrial hyperplasia of severe complexity, all of which can cause prolonged menstruation. Therefore, it is important to pay attention to this situation. It is recommended to do ultrasound examination to understand whether there are abnormal echogenic masses in the endometrium, and if necessary, diagnostic scraping is also needed.