If you notice bright red or dark red blood coming out of your stool, or if you notice blood in your stool, it means you have blood in your stool. Not only that, but if your stool is black or tarry in color and you have not recently consumed foods or medications that can make your stool black, such as pig’s blood, you should also be experiencing blood in your stool. Blood in the stool is most likely an initial warning of an anal disease and is commonly seen in the following anal diseases: Hemorrhoids: characterized by blood in the stool mostly after defecation, bright red blood in the form of dripping or spraying, usually painless; Anal fissures: characterized by tearing or knife-like pain during defecation, the pain often lasts for several minutes or hours after defecation, blood in the stool is bright red, there are also a few anal fissures that are painless; Rectal polyps: commonly found in minors. The blood is bright red and attached to the surface of the stool. It may be rectal cancer if the blood in stool is dark red in color, mixed with mucus or pus, attached to the surface of stool or mixed with feces, combined with increased frequency of defecation, incomplete defecation, thinning and deformation of stool; if it is colon cancer, it may be combined with abdominal pain or wasting, and dark red blood is mixed with stool; at this time, it is necessary to go to the hospital in time to perform colonoscopy and other examinations to determine whether there is malignant tumor. If it is colon cancer, it may be combined with abdominal pain or weight loss and dark red blood in the stool. Of course, there are many other diseases that can cause blood in the stool, including many systemic diseases such as hematologic diseases, which require you to seek medical attention to find the cause.