Blood in the stool is the discharge of blood from the anus. Blood in the stool, or all blood in the stool, bright red, dark red or tarry in color, is called blood in the stool. Blood in stool is usually seen in the lower gastrointestinal tract, especially in the colon and rectum, but occasionally it is seen in the upper gastrointestinal tract. The color of blood in the stool depends on the location of the bleeding, the amount of bleeding, and how long the blood stays in the intestine. Causes of blood in stool Almost all GI bleeding can cause blood in stool, but there are two common causes of blood in stool: (a) “False blood in stool” False blood in stool is caused by the discoloration of stool after eating certain foods and drugs. For example, after taking iron, carbon, bismuth, herbal medicine, or eating pig liver, animal blood, tomatoes, beets and other foods, the stool can be dark brown, black or red. Sometimes bleeding in the mouth or nasal cavity can also cause a change in stool color after swallowing. These are pseudo-blood in the stool, after stopping the use of drugs and food, the “blood stool” will disappear. (2) “Real blood in stool” For real blood in stool refers to blood in stool caused by anal and intestinal diseases, hemorrhoids, anal fissures, rectal polyps, colon polyps, ulcerative colitis and even colon cancer, rectal cancer, etc. will appear the symptoms of bleeding in stool, so we should pay attention to it. 1, “bright blood-colored blood stool” – benign causes are more common Mostly acute (immediate) bleeding, blood flows out of the blood vessels for a very short time through the anus with the feces, or directly after the stool. The blood is similar in appearance to traumatic bleeding, bright red or purplish red or dark red in color, and can coagulate into clots after a little time. (1) Hemorrhoids: External hemorrhoids and mixed hemorrhoids of all stages can cause bleeding in the stool, usually with fresh blood in the stool or dripping blood after the stool. External hemorrhoids usually do not bleed in the stool. (2) Intestinal polyps: Painless fecal bleeding. The amount of bleeding varies. Generally, the blood does not mix with the stool, or the polyp may mix with the stool if the polyp is in a high position and the number is large. (3) Rectal prolapse: anal swelling repeatedly prolapses, and bleeding during defecation may occur after a long period of illness. (4) Anal fissure: bleeding in the form of blood attached to one side of the fecal surface, not mixed with feces, and some patients dripping blood after defecation. 2. “Stool with pus and blood and mucus” – beware of intestinal cancer! That is, there is both pus (mucus) and blood in the excreted stool. Pus (mucus) blood stool is often seen in the rectum or colon tumors and inflammatory diseases. The following diseases are common: (1) rectal cancer: blood is fresh or dark red, mucus may be present in the stool, and blood, mucus and stool are often mixed together. (2) Colon cancer: the first symptom can be stool bleeding (especially tumors in the left hemicolectomy), mostly bloody stool with pus or mucus, dark blood color, accompanied by abdominal mass, abdominal pain, chronic progressive wasting and other symptoms. (3) Ulcerative colitis: longer history, recurrent episodes of mucus stools or pus and blood stools, accompanied by left lower abdominal pain or lower abdominal pain. (4) intestinal infectious diseases: such as bacterial dysentery, amoebic enteropathy, etc. 3, oily black shiny stool – is your stomach okay? Also known as tarry stools, black or brownish-black stools. One of the most common symptoms of upper gastrointestinal bleeding: such as gastric ulcers, duodenal bulb ulcers, etc. If the bleeding is small and slow, the blood stays in the intestine for a long time, the discharged stool is black; if the bleeding is large and stays in the intestine for a short time, the discharged blood is dark red; the bleeding is particularly large and can also be bright red when discharged quickly. 4, the naked eye can not see the blood stool – the latent blood stool is more terrible! A small amount (trace) of gastrointestinal bleeding will not cause a change in the color of the stool, only positive in the stool occult blood test, called occult blood stool. Occult blood stools can occur in all diseases that cause GI bleeding, commonly ulcers, inflammation and tumors. The stool occult blood test detects a small (trace) amount of blood in the stool. Regular stool occult blood testing is an important way to screen for colorectal tumors (primary screening). The danger of blood in stool Blood in stool can easily make the body lose a large amount of iron and cause iron deficiency anemia. In case of severe anemia, pallor, fatigue, loss of appetite, palpitation, rapid heart rate, shortness of breath after physical activity, swelling, etc. Some patients may even have neurological symptoms such as agitation, excitement, irritability, etc. At the same time, blood in stool is also an early signal of intestinal malignant tumor. Since the situation of blood in stool is similar to hemorrhoid bleeding, it is difficult for people to distinguish it, and some people do not pay enough attention to it, so it is easy for early malignant tumor to be easily ignored and become a tragedy. What should I do if I have blood in stool? People generally believe that bleeding stools are caused by hemorrhoids, which is incorrect. Hemorrhoids, especially first and second stage internal hemorrhoids, mostly have blood in their stool as the main symptom. Blood in the stool usually occurs during defecation, dripping or jet-like bleeding during and after defecation, blood does not mix with feces, and repeated bleeding can lead to severe anemia. The diagnosis of hemorrhoids is relatively easy, but it must be noted here that anorectal diseases with symptoms of blood in the stool, such as rectal adenoma and colorectal cancer, are often misdiagnosed as internal hemorrhoids in clinical practice, so other intestinal or even systemic diseases must be excluded when determining the diagnosis of hemorrhoids. In addition to asking the patient’s medical history and performing routine physical examination, it is necessary to perform a detailed specialist physical examination for patients with hemorrhoids: for example, anal finger examination by a specialist, disposable anoscopy, disposable trocar proctoscopy, etc. These examinations are convenient, economical, safe and accurate. In addition, for patients who have a family history of inflammatory bowel disease (IBD), intestinal tumor, or a long history of disease and other risk factors, clinicians often recommend patients to perform e-colonoscopy or abdominal CT for examination and diagnosis.