Generally, menstruation lasts 2-8 days, 4-6 days on average, the amount of menstruation is around 20-60 ml, and the menstrual cycle is between 21-35 days. If the menstrual period lasts less than two days and the menstrual flow is less than 20 ml, it belongs to menorrhagia, which is mostly caused by low estrogen or thin endometrium, which may affect the future pregnancy and easily affect the fertilized egg implantation, it is recommended to draw blood for hormone test to see endocrine condition, and ultrasound is needed to understand the thickness of the endometrium. If the menstrual period lasts for more than 8 days, and the menstrual flow is over 80 ml, it belongs to excessive menstrual flow, which is usually caused by uterine hypertrophy, uterine fibroids, endometriosis, or endocrine disorders, and ultrasound is needed to know the condition of uterine adnexa, and endocrinology examination is needed if necessary.