In my clinic, there are many patients who come to see me for blood in the stool. Most of these patients come to see me because they are worried about whether they have bowel cancer. Of course, most of them are not bowel cancer, but they are just worried about themselves. So, is there any relationship between blood in stool and bowel cancer? What kinds of blood in stool should be highly alerted to bowel cancer? There is still a need for further science education. Learn to distinguish the nature of blood in stool From the nature of blood, we can roughly distinguish whether it is bleeding from hemorrhoids or bowel cancer. The formation of hemorrhoids is simply due to the varicose veins in the anus. Since the hemorrhoid vascular group is very close to the anal opening, or even at the anal opening, it will show when the patient holds his breath and exerts himself before the stool, due to the contraction of the anal sphincter, the squeezed vascular group ruptures and appears to drip or even spray blood, and after the stool, the anal sphincter reflexively contracts and again drips blood, which is discharged in steps with the stool. Therefore, hemorrhoid bleeding is characterized by dripping or squirting blood and separation of blood in stool. The bleeding of bowel cancer is generally chronic bleeding of tumor in the intestinal cavity, and the bleeding of tumor is not sprayed or dripped out in most cases, but mixed in the stool, and it will not be bright red, but dark red, and the tumor will not only break and bleed, but the broken surface will also be secondary to infection, inflammatory exudation, and mucus, which will make the water red when the toilet flushes the stool. Therefore, the characteristics of blood in stool of bowel cancer are: mucus dark red blood stool and mixed blood in stool. If the blood in stool occurs due to constipation, straining to defecate, and fresh blood, it is mostly due to hemorrhoids, and if it is accompanied by pain, there may also be anal fissure. If there is no obvious cause, along with increased frequency of stools, a feeling of falling, change in stool habits, or accompanied by bloating, weight loss, etc., plus dark red stools, it is time to rule out intestinal cancer at the hospital. In addition, there are some middle-aged and elderly patients who take anticoagulant drugs such as aspirin and warfarin because of brain attack or heart disease, and they have a lot of blood in stool one day, so they should be alert to the possibility of bowel cancer and be investigated in time. Because as mentioned before, bowel cancer is usually chronic blood loss, small amount and mixed in stool, which is not easy to detect, but after long-term oral anticoagulant, coagulation function and platelet aggregation become poor, which will cause more bleeding from tumor. 3. Be alert to the high-risk group of bowel cancer Patients over 40 years old should be highly alert to the possibility of bowel cancer and must seek medical consultation in time if they have the following conditions: a history of colon or intestinal cancer in first-degree relatives; a history of intestinal polyp, adenoma or cancer; persistent positive fecal occult blood; a history of mucus and blood stool, chronic constipation and chronic diarrhea. For the above patients, if they have blood in the stool, they need to go to the hospital promptly for examination and colonoscopy and other tests.