Auntie generally refers to menstruation, and a girl’s menstrual blood is usually dark red in color, slightly darker than venous blood. Menstruation is a physiological phenomenon that occurs when the uterine lining sheds its blood and bleeds periodically as a result of cyclical changes in the ovaries. Menstrual blood is dark red and slightly darker in color than venous blood. Half of menstrual blood is blood, and in addition to blood menstruation also contains vaginal secretions, cervical mucus, and endometrial tissue. In addition to blood, it contains vaginal secretions, cervical mucus, endometrial tissue, etc. When the bleeding is fast or heavy, there may also be blood clots. Normal menstrual flow is usually 20-60 ml and usually lasts for 2-8 days. It is recommended to go to the hospital in case of abnormalities in the amount, color, and duration of menstruation.