Rectal cancer patients usually do not have obvious characteristics of defecation. Rectal cancer is mainly about the change of patients’ defecation frequency and defecation habit, and there may be blood in stools, for example, patients’ stools are shaped once in 2-3 days before they get sick, if there is rectal cancer, patients may have more frequent stools, 2-3 times a day, and unshapely and dilute stools. If the tumor surface breaks down with bleeding, it will show blood in stool, usually the blood is mixed on the surface of stool, sometimes it is dark red blood, sometimes it is bright red blood, it is recommended to perform colonoscopy or anorectal diagnosis, and combined with abdominopelvic CT examination to clarify if necessary.