Constipation is a common symptom of the gastrointestinal tract in which the number of bowel movements decreases, the volume of stool decreases, the stool is dry and straining to defecate. Blood in stool is often a serious complication of constipation that is not treated in time and has been prolonged for a long time. Most constipation and blood in stool is due to dry stool, prolonged defecation, anorectal congestion, plus dry stool cutting through the rectal mucosa eventually leading to blood in stool. Clinically, it is mostly manifested as hemorrhoids and anal fissures. Of course, there are also other causes, such as intestinal polyps and colorectal cancer, which can also cause constipation and blood in stool, and are often accompanied by changes in the shape of stool. When you find constipation and blood in the stool, you should first carefully observe the color and nature of the blood in the stool, and then find out what causes it. Blood in the stool includes blood on the surface of the stool (bright red, dark red can be caused by hemorrhoids, anal fissures and intestinal polyps), occult blood in the stool (a small amount of bleeding is not visible to the naked eye in the stool, and occult blood can be detected in routine stool), and black stool (mostly caused by bleeding in the upper gastrointestinal tract). Therefore, depending on the symptoms of constipation and blood in the stool, the diseases that are indicated may also be different. Blood in stool and constipation requires prompt medical attention. Blood in stool is an “alarm” sign of constipation, so constipation and blood in stool should be taken seriously, and the cause should be identified early and treated effectively according to the condition.