The presence of blood in the stool test may be related to menstruation and digestive disorders. 1. Menstruation: During menstruation, women will experience vaginal bleeding due to the shedding and bleeding of the uterine lining. If you have a stool test at this time, the stool may be contaminated by the menstrual blood and appear bloody. 2. Digestive system diseases: If you suffer from internal hemorrhoids, anal fissure, ulcerative colitis, bacterial dysentery and other digestive system diseases, intestinal mucosa or anal bleeding will lead to blood discharge with the stool, and there may be blood in the stool. There are more reasons for blood in the stool during laboratory tests, so it is recommended to consult a doctor in time to clarify the cause of the disease, so as to avoid adverse effects.