Blood in Stool – Causes, Symptoms and Treatment

The blood that appears mixed with the feces or separated from these is a symptom that can have very different causes. The blood, visible or hidden, comes from hemorrhages in the gastrointestinal tract. If blood is detected in the stool, always go to the doctor to determine its origin, it is also one of the common symptoms of colon cancer.

The medical definition of blood in the stool establishes the following differentiation:

Blood is hidden in the feces: the presence of blood not visible in fecal matter, which can only be detected by a clinical test called the guayac test.

Melena (tarry stools): black stools and foul odor as a result of bleeding in the upper digestive tract (upper gastrointestinal bleeding).

Hematochezia: evacuations mixed with clear and dark blood.

Rectal bleeding: stools accompanied by light red blood, due to bleeding in the lower intestinal tract (low gastrointestinal bleeding), hemorrhoids or severe bleeding in the upper parts of the digestive tract.


The presence of blood in the stool can be due to several causes. It is common that people who detect blood mixed with their stools or covering them are frightened and fear that it is intestinal cancer. However, there are many inconsequential causes that cause the appearance of blood in the stool. In any case, it is advisable to go to the doctor to clarify the specific causes, since it may be something harmless, but also be a symptom of a serious illness or an emergency that endangers the life of the affected, such as colon cancer.

The existence of bright red blood covering the stool is often due to hemorrhoids. The blood can also be the result of small tears in the mucosa (fissures). Anal fissures are common in chronic inflammatory bowel diseases such as Crohn’s disease or ulcerative colitis.

Other possible causes of the presence of blood in the stool are intestinal diverticula, intestinal polyps, intestinal cancer (colorectal cancer), and less frequently blood diseases, inflammation of the blood vessels (vasculitis) and vascular malformations of the colon. (Angiodysplasia).

The manes, or tarry stools, are caused by a hemorrhage in the upper digestive tract (upper gastrointestinal bleeding). Due to the contact of the blood with the gastric acid, the fecal matter acquires a black coloration. Bleeding in the upper digestive tract is caused mainly by an ulcer, for example, a gastric ulcer or a duodenal ulcer. Esophageal hernias, in which parts of the stomach move into the thorax (for example, hiatus hernia), as well as esophageal varicose veins, can lead to gastrointestinal hemorrhages and, therefore, in the presence of blood in the stool.


When blood is detected in the stool, the most important thing is to detect the source of the bleeding as soon as possible in order to stop the bleeding. Especially in the case of severe and sudden hemorrhages, for example in gastric ulcers or esophageal varicose veins, it is essential to act quickly. The treatment, therefore, basically depends on the cause of the bleeding.

If the presence of blood mixed with the stools or covering them is a consequence of hemorrhoids, the use of ointments and suppositories is useful in case of mild discomfort. If the discomfort is greater, you can choose to obliterate the hemorrhoids (sclerotherapy) or eliminate them completely. Intestinal polyps and intestinal diverticula are removed by surgery, usually performed with an endoscope. If the bleeding is caused by intestinal cancer, a specific treatment is required (for example, surgery, chemotherapy or radiotherapy).