The black scum inside the menstrual period should be the shed endometrial debris. Menstruation is caused by a decrease in the secretion of estrogen and progesterone in the body after ovulation, causing the endometrium to shed without the support of sex hormones. The endometrium is shed and bleeds locally to form menstruation, which contains blood mixed with shed endometrial debris. During menstruation, women need to pay attention to rest, avoid straining and staying up late, pay attention to regular rest habits to ensure sufficient sleep, appropriate regular exercise can promote the smooth circulation of menstrual blood. Pay attention to keep the small abdomen warm to avoid cold, so as not to cause menstrual blood stagnation caused by dysmenorrhea. During menstruation, you need to do a good job of cleaning and sanitation of the vulva to avoid infection, and you need to avoid intercourse to avoid cavity infection and excessive menstrual flow, as well as endometriosis and other diseases that affect women’s health.