Blood in stools is when blood is discharged from the anus and the stools are bright red, dark red or tarry in color (black stools). Blood in stool is only a symptom, not a disease. Strictly speaking, blood in stool can be caused by bleeding from any part of the digestive tract, such as the mouth, biliary tract, gastrointestinal tract and anus. However, blood in stool is mostly seen in lower gastrointestinal bleeding, such as colon, rectum and anal lesions. So what kind of disease may we have once we have blood in stool? Below we recognize the meaning of this danger signal from the different characteristics and accompanying symptoms of blood in stool. 1. Fresh blood in stool: Fresh blood in stool is mostly acute hemorrhage, and the blood is discharged with feces through the anus in a short period of time after it flows out of the blood vessels, or it flows out directly after the stool. The appearance of the blood is similar to traumatic bleeding, and it can solidify into blood clots after a long time. (1) Internal hemorrhoids: all stages of internal hemorrhoids can cause bright red blood during or after defecation, usually feces or stool paper stained with fresh blood, serious blood can appear after defecation, blood, painless, intermittent or recurrent episodes. (2) Rectal polyp: painless blood in stool, common in children. Bleeding during defecation, stop after the end of defecation, the amount varies, and generally the blood is not mixed with feces. The blood is not mixed with feces. Low rectal polyps can be prolapsed out of the anus after defecation. (3) Anal fissure: The bleeding is in the form of blood on the surface of feces, which is not mixed with feces or only stained with blood on the stool paper, and patients with more bleeding may have blood dripping after stool. Its obvious characteristic is that it is accompanied by tearing or cutting pain in the anus during and after defecation, and the pain after defecation can last for several minutes or hours. (4) External hemorrhoids: generally not easy to bleed, inflammatory external hemorrhoids or thrombosed external hemorrhoids may bleed from anus after rupture, which is not related to defecation, and there is swelling and pain at anus, and skin ulcers can be seen on the surface. (5) Cancer of anal canal: fresh blood when defecating, hard mass in anus, painless in early stage and painful in late stage. (6) Anus trauma or foreign body in anus: if accidental sharp object is stabbed into anus or swallowed fish splinter, date kernel, shell and other foreign bodies stuck in anus, it may cause pain and fresh blood in stool, and there may be pus and blood in case of infection. 2, pus and blood or mucus blood stool: that is, there are both pus (mucus) and blood in the feces. Pus (mucus) and blood means feces mixed with mucus, pus and blood. The following diseases are common: (1) Rectal cancer: blood is fresh or dark red, mucus can be found in feces, and often blood, mucus and feces are present at the same time, sticking and staining each other, but not completely mixed. It may be accompanied by changes in stool shape and bowel habit and obvious rectal irritation symptoms, increased frequency of stools, urgency and heaviness. (2) Colorectal cancer: with the prolongation of the disease, bleeding in stool gradually occurs, which is mostly bloody stool containing pus or mucus, with dark color, and can be mixed with feces. (3) Non-specific inflammatory bowel disease: such as ulcerative colitis, the attack often has mucus stool or pus and blood stool, feces and mucus, pus and blood are completely mixed, accompanied by left lower abdominal pain or lower abdominal pain, and the feces can be passed several times to dozens of times a day. (4) Perianal abscess rupture: there is often pus and blood flowing from the anus or paranal ulcers, which is not related to defecation, and may be accompanied by obvious pain and fever and other symptoms. (5) intestinal infectious diseases: there may be mucus, pus and blood stools, accompanied by obvious urgency, fever and malaise, such as bacillary dysentery, amoebic enteropathy, etc., through the feces to find pathogens to make a clear diagnosis. 3, black stool: also known as tarry stool, stool is black or brownish black. It is one of the most common symptoms of upper gastrointestinal bleeding. Bleeding from the esophagus, stomach, duodenum and biliary tract is common. If the amount of bleeding is small, and the bleeding rate is slow, the blood stays in the intestine for a long time, the discharged feces is black; if the amount of bleeding is large, and stays in the intestine for a short period of time, the discharged blood is dark red or purplish-red; the amount of bleeding is particularly large, and it is often accompanied by vomiting blood. In addition, black stools can also be seen in the consumption of animal blood products, liver or taking certain drugs such as iron, bismuth and carbon. 4, occult blood: a small amount or trace of gastrointestinal bleeding will not cause stool color changes, only in the fecal occult blood test was positive, known as occult blood stool. All diseases that cause gastrointestinal bleeding can cause occult blood in the stool, and ulcers, inflammation and tumors are common. The fecal occult blood test detects small or trace amounts of blood in the stool. Early fecal occult blood of intestinal polyps (cancer) can be positive, regular fecal occult blood test is an important way of colorectal tumor screening. 5.Blood in stool: accompanied with bleeding phenomenon of skin, mucous membrane or other organs, mostly seen in hematologic diseases and other systemic diseases, such as leukemia, hemophilia, disseminated intravascular coagulation and so on. So if you find yourself blood in stool, you must pay attention to it, even if it is a benign disease, long-term blood in stool will cause anemia, which will cause serious damage to various organs of the body, and even affect the work, study and life, and if it is a malignant disease, it will threaten the life, so once the body sends out the danger signals of blood in stool, please go to the relevant departments in time for medical treatment, so as not to make mistakes in medical condition and regret for the rest of your life.