There is no obvious symptom in early stage of rectal cancer, but when the cancer breaks down or combined with infection, patients will have blood in stool. Blood in stool of rectal cancer is dark red or light red blood in stool. If there is blood in stool and combined with the feeling of urgency and incomplete bowel movement, it is highly suspected to be colon cancer. Bleeding of rectal cancer worsens with the progress of disease, lasts longer and longer, has no obvious relationship with diet, and is intermittent. One should pay attention to differentiate it from hemorrhoids, which bleeds in bright red color, drips or jets blood after bowel movement, and the bleeding stops after bowel movement.