It is often said that “nine out of ten men have hemorrhoids” and “ten out of ten women have hemorrhoids”. It is not uncommon to have some blood in your stool, but have you ever thought that sometimes accidents can happen if you are a little careless? The first thing you need to do is to get a good idea of what you are getting into. Some time ago, Mr. Dong often found a small amount of dark red blood in the stool, at first thought that the heat, coupled with the diet is too spicy, so that the hemorrhoids relapse. He then asked his wife to give him some hot soup to clear the fire, but also a series of days to drink herbal tea. However, the tricks that worked in the past did not work this time. His blood in the stool not only did not see a reduction, but also seems to be more and more frequent. His wife finally couldn’t resist and forcibly stopped him from going to Beijing to attend an academic conference, forcing him to go to the hospital. The attending doctor performed a rectal finger examination and then asked him to perform a fecal occult blood test and suggested that he undergo further colonoscopy. Mr. Dong was impatient and thought the doctor was making a big deal out of it, saying he had a lot of things to do and didn’t have time to do a colonoscopy and asked the doctor to prescribe him some medicine according to the hemorrhoid blood in stool. The attending doctor seriously and patiently explained to him the possibility of blood in stool and the necessity of examination, and finally, Mr. Dong underwent colonoscopy and pathological biopsy, which confirmed that it was rectal cancer. Fortunately, due to early detection, timely and effective measures, the subsequent treatment was effective and Mr. Dong’s recovery progressed very well. The most common cause of blood in the stool is hemorrhoids, the incidence of which is very high. Hemorrhoids are actually soft venous masses formed by the expansion and flexion of the venous plexus under the mucous membrane and skin at the end of the human rectum. The blood in the stool can be caused by the feces rubbing the mucous membrane of the hemorrhoid nucleus and damaging the submucous blood vessels, or by the excessive force of defecation, which increases the pressure in the blood vessels and causes the varicose veins to rupture. Hemorrhoid blood in the stool can occur during the whole process of defecation, but most of them show bleeding after the stool, bright red (if there is more bleeding, the blood is retained in the intestinal cavity and can be dark red when it is discharged, even with blood clots). If the amount of bleeding is small, it may appear as blood in the stool or blood on the paper; if the amount is large, it may appear as dripping blood, or jet-like bleeding from a certain area. Hemorrhoids are mostly found in sedentary or standing people, such as institutional workers, white-collar workers, drivers, etc. They are often triggered by eating spicy and fried foods, as well as constipation, fatigue, alcohol consumption, anal inflammation, etc. Pregnant women are also vulnerable due to increased abdominal pressure, which affects blood reflux. Colon and rectal cancer is another important cause of blood in stool. In recent years, with the improvement of living standard and the change of diet structure, the incidence of colon and rectal cancer in China has increased significantly, mostly seen in middle-aged and elderly people aged 40-60, with the peak incidence around 50 years old, often with bloody stools as the prominent manifestation. If the lower colon or rectal cancer is rotten and necrotic, mucus-purulent-blood stool, urgency, and special fishy smell of stool may appear; if the distal colon cancer causes narrowing of intestinal cavity, stubborn constipation or thin and flattened stool may appear, and the patient may also have abdominal pain, abdominal mass, anemia, emaciation, weakness and other symptoms. Since the early symptoms of colon and rectal cancer are more similar to hemorrhoids, it is not uncommon to misdiagnose and delay the diagnosis of colon and rectal cancer blood in stool, which deserves the high attention and vigilance of both clinicians and patients. In fact, sometimes a simple rectal finger examination can reveal the clues, and if necessary, combined with colonoscopy and biopsy, most of the intestinal lesions can be hidden. Many people are reluctant to face the examination, probably because of shyness, fear of pain, too expensive and other reasons, but now painless colonoscopy has been born, as colonoscopy is no longer as unbearable as in the past. For the sake of health, it is worth it. Blood in the stool is a manifestation of gastrointestinal bleeding. Depending on the site of bleeding, the amount of bleeding, and the time the blood stays in the digestive tract, blood in the stool can be bright red, dark red, tarry, or occult blood (note: a small amount of bleeding in the digestive tract may not cause a change in the color of the stool, but only a positive occult blood test in the stool, which is called occult blood stool). Generally speaking, bleeding from the rectum, anus, colon, and other areas close to the anus are more likely to appear as fresh blood-like stools or dark red blood. If the upper gastrointestinal tract (such as the stomach, duodenum, etc.) bleeding is not vomited, the blood stays in the intestine for a longer period of time, and the hemoglobin in the blood combines with sulfide in the intestine to produce ferrous sulfide, the stool will be dark and shiny, which is called tarry stool. However, it should be noted that the consumption of certain foods, such as pig’s blood, pig’s liver, herbs such as shouwu, dihuang, etc., can also make the stool black and tarry, this situation is not blood in the stool, can be distinguished by the stool occult blood test, positive for bleeding. If the upper gastrointestinal bleeding is large and the blood does not stay in the intestine for a long time, dark red or bright red blood in the stool can also be seen.