Normal menstrual blood is bright red or dark red non-clotting blood, a little brown may appear on the first day of menstruation or one to two days before the end of menstruation endometrial stripping of the amount of small in the uterus to stay in the uterus for a long time, is a normal physiological phenomenon. Menstruation is a process in which the endometrium peels off, bleeds, and gradually repairs itself. Therefore, menstrual blood will contain a small amount of endometrial debris, cells shed from the cervix and vagina, and cervical mucus. Normal menstrual period can last two to seven days, if the whole period is only a little brown and the bleeding is less than five ml, it is considered that the menstrual flow is too small, you should carry out ultrasound of uterine adnexa, sex hormone six and other related examinations to exclude the organic pathology of the uterus. It may also be caused by endocrine dysfunction, according to the results of the examination and then carry out symptomatic treatment.