The phrase “good teeth, good appetite” makes people pay more attention to dental health, which is the topic of “import”; however, the “export” of the problem, not many people care about, I do not know However, not many people are concerned about the issue of “export”, not knowing that “bad stool is like a mountain of disease”. Stool is imported food in the human gastrointestinal tract under the action of a series of digestive enzymes after digestion and absorption of the product, usually yellow, its main components are water, food residues, crude fiber, bile pigments, etc.. The surface of the formed stool is covered with a layer of mucus secreted by the intestinal glands, which acts as a lubricant and facilitates the discharge of stool from the body. If the color, shape and nature of the stool has changed, the problem is not small, may be related to the following diseases: 1, biliary tract disease Biliary system includes intrahepatic bile ducts and extrahepatic bile ducts. The extrahepatic bile duct is the connection between the liver and the intestine, and is also the way for bile secreted by liver cells and bile ducts to enter the intestine. Stones in the extrahepatic bile duct or tumors in the extrahepatic bile duct (sometimes pancreatic head cancer infiltrates and compresses the extrahepatic bile duct) can cause obstruction to the extrahepatic bile duct, and bile cannot enter the intestine smoothly but is forced into the bloodstream, forming jaundice. As the bile pigment in bile makes the stool yellow, the significant decrease of bile pigment in the intestine makes the yellow color of stool lighter or white. 2, gastrointestinal tract diseases The gastrointestinal tract usually refers to the stomach, small intestine and large intestine. Small intestine includes duodenum, jejunum and ileum; large intestine includes cecum, colon and rectum. The gastrointestinal tract is a tubular structure, and the gastrointestinal wall is divided into a plasma membrane layer, a muscular layer, a submucosal layer and a mucosal layer. When lesions occur in the innermost mucosal layer, leading to gastroduodenal ulcers and gastrointestinal tumors, the stool will have blood in it, the stool will be brown or black, and the stool will become thin, mucus and blood, or pus and blood. When rectal cancer occurs, the stool becomes deformed and thin, accompanied by frequent bowel movements, anal swelling or a sense of incomplete stool, which is a symptom caused by the infection of the tumor surface; the frequency of symptoms is 80-90% for blood in stool, 60-70% for frequent stool, 40% for thin stool, 35% for mucus stool, 20% for anal pain, 20% for a sense of incomplete stool, and 10% for constipation. 3, anal disease anal refers to the site of stool discharge, that is, the anatomical anal canal, from the dentate line, down to the edge of the anus, about 3-4 cm long. The upper part of the inner layer of the anal canal is migratory epithelium and the lower part is keratinized compound flat epithelium. The outer layer of the anal canal is the internal and external sphincter that surrounds the anal canal. The inner sphincter is a thickened circular muscle of the intestinal wall, which is a non-random muscle; the outer sphincter is a circular transverse muscle surrounding the anal canal, which is a random muscle and is divided into subcutaneous, superficial and deep parts. When hemorrhoids or anal fissures occur in the anus, there will be bright red stools or blood dripping after the stool, and sometimes there is pain when relieving the stool. In summary, changes in the color, shape and nature of the stool are important manifestations of biliary, pancreatic, gastrointestinal and anal diseases, and should be taken very seriously, otherwise they may lead to serious consequences. It can be said that “bad stool is like a mountain of disease”.