If the intestinal mucosa is damaged and detached, the stool must be bright red, with blood in the stool in low level and dark red in high level, but the intestinal mucosa is rarely detached and is extremely rare in clinical practice. The damage to the intestinal mucosa can have ulcers or tumor infiltration. High-grade tumors usually have obstruction, shapeless bowel movements, abdominal pain, and mild blood in the stool. In addition, in ulcerative colitis, there are also changes in the nature of the bowel movements, including increased mucus and mild blood in the stool. Rarely, Crohn’s disease of the colon is also manifested by changes in the shape of the stool, such as blood in the stool and mucus in the stool.