Blood in the stool is a relatively common symptom of anorectal diseases, constipated patients are often panicked by the discovery of fresh blood in the stool or blood dripping from the anus after the stool, do not know the specific disease, indiscriminate use of drugs, afraid to come to the clinic, so that the condition is delayed. Today I will give you an introduction to the relevant anorectal diseases, causing constipation with fresh blood of the common diseases are mainly the following 1, hemorrhoids bleeding hemorrhoid patients, due to pain in the anus when defecating, often inhibit the stool, gradually produce constipation, constipation and to a certain extent aggravate the hemorrhoids. When the nucleus of the hemorrhoid is larger, the mucosal tissue of the hemorrhoid becomes thinner, and the dry fecal mass tends to rub the mucosa of the hemorrhoid when defecating, causing blood in the stool. It is characterized by forceful defecation, blood from the anus, fresh blood often attached to the surface of the stool, after the stool can have anal drip blood, or hand paper with fresh blood. 2, colonic diverticulum bleeding colonic diverticulum is the wall of the colon protrudes outward to form a pouch. It can be a single, but more often a series of sac-like protrusion from the intestinal lumen outward. The manifestation is sudden massive bleeding, bright red, with blood clots. 3, isolated rectal ulcer bleeding, also known as benign isolated rectal ulcer, benign non-specific rectal ulcer, is due to benign isolated acute and chronic ulcers of the anterior rectal wall caused by gastrointestinal disorders, with abdominal pain, constipation, diarrhea, pus and blood stool as the main manifestation, most of the symptoms are blood on the surface of the stool with pain in the anal region. 4, anal fissure bleeding constipation caused by anal fissure, constipation further aggravated, in the force of defecation, dry stool expansion of the anal canal, can make the anal canal small blood vessels tear and bleeding, characterized by a small amount of bleeding, or blood on the surface of the stool, or blood dripping out when defecating, or blood on the hand paper after the stool. Another characteristic is that patients with anal fissures often have severe tearing anal pain. Therefore, when there is periodic severe anal pain caused by defecation with blood in the stool, anal fissure should be considered. 5, colon polyps, especially rectal polyps bleeding, most people have polyps formed in the intestinal mucosa, but no conscious symptoms, because small polyps are just raised nodules in the intestinal mucosa. Large polyps are often small tumors with tips that protrude into the intestinal cavity and can move up and down in the intestine, and due to fecal pressure and stimulation, the surface often has ulcers, erosions, and even bleeding. Bright red blood can be seen on the surface of feces, or mixed with feces, or mixed with mucus and purulent secretions. Rectal polyps often manifest as painless blood in stool, generally small amount of bleeding, when there are larger polyps in the colon, it can cause intussusception, lower abdominal cramps, constipation aggravated, and blood in stool. 6.Colorectal cancer includes rectal cancer, sigmoid colon cancer, colon cancer, whose main symptom is blood in stool. If the cancer is located in the right half of the colon, such as ileocecal, ascending colon, colonic liver flexure, it is generally not easy to see obvious bleeding, but mainly positive fecal occult blood; if the cancer is located in the left half of the colon, the color of fecal blood is mostly bright red or dark red, attached to the surface of the feces, if the amount of bleeding is not much, due to constipation in the intestinal cavity retention for too long, the blood is dark, blood mixed with feces. Sigmoid colon cancer often manifests as alternating constipation and diarrhea, with fresh blood, pus and mucus in stool; rectal cancer is blood in stool or pus-blood stool, or mucus-blood stool with bloody secretions in stool. In short, fresh blood in stool indicates that the bleeding site is in the gastrointestinal tract below the large intestine, especially in the sigmoid colon, rectum and anus of the left half of the colon. Blood in stool is an important symptom that should not be ignored and should be treated promptly.