1, hemorrhoids: bright red blood in the stool, attached to the surface of the fecal mass; or blood dripping before and after the stool, serious jet, easy to occur when the stool is constipated. 2, anal fissure: blood in the stool is less, bright red color; defecation anal pain, so that the patient dare not defecate. 3, polyps: blood in stool without discomfort, normal fecal quality, blood often attached to the surface of the fecal mass. Easily carcinogenic. 4, ulcerative colitis, proctitis: increased stool, pus and blood stool mixed with mucus stool, abdominal pain, anal drop. 5, colorectal cancer: early blood in the stool only, medium-term persistent, chronic mucus blood stool, mixed with feces, frequent bowel movements, sometimes only some blood or mucus and no feces. About 80% of rectal cancers have blood in stool. The early stage of colorectal cancer lacks specific manifestation, and some patients only show habitual change of stool and blood in stool of different degrees, so it is often misdiagnosed as hemorrhoids and so on. Therefore, blood in stool should be further examined in anorectal department. Anal finger examination is the simplest examination method, and 70% of rectal cancer can be detected through this examination. Proctoscopy or sigmoidoscopy, fiberoptic colonoscopy can also be used for clear diagnosis.