Menstruation is usually referred to as menstruation, and the low blood volume of menstrual flow may be related to the condition of the uterus as well as endocrine abnormalities in the organism, such as polycystic ovary syndrome and other factors. The amount of menstrual flow is an important indicator of the normalcy of a woman’s body. If the bleeding is too much or too little, it is not normal, and the normal amount of menstrual flow should be about 20-60ml. If the amount of blood is low, it may be related to the following reasons: 1. Uterine condition: If the body has recently had abortion or scraping surgery, the bleeding may be reduced due to the irritation of the uterus, such as cervical adhesion, endometritis and so on. 2. Abnormalities of endocrine system: If you often have low menstrual bleeding or early or delayed menstrual period, it may be caused by abnormalities of the endocrine system, which is mostly seen in polycystic ovary syndrome or hyperprolactinemia, and it is recommended to do a full set of female sex hormone tests to clarify the cause. There may also be other reasons for low menstrual bleeding, so it is recommended to go to the hospital in time for a complete examination to clarify the cause of the problem, and then give targeted treatment or therapy.