After abortion, the first menstrual period is not clean for more than twenty days, and the following reasons are often seen clinically: First, endometrial inflammation, resulting in brittle endometrial tissue, prolonged vaginal bleeding, often accompanied by pain in the lower abdomen or the color of the menstrual blood becomes lighter. Second, endocrine disorders after abortion lead to prolonged menstruation, mainly caused by estrogen deficiency. Third, abortion is not done cleanly, resulting in prolonged menstrual period, it is recommended to do ultrasound examination to find out whether there are residual tissues in the uterus, and must be given positive treatment. The above is the reason why the menstruation is not clean for more than twenty days in the first month after abortion, and it is recommended to do the corresponding examination.