Bright Red Blood In Stool Causes

You may have rectal bleeding or hematochezia, a condition wherein bright red blood passes through the anus, often mixed with feces and or blood clots. The condition is called rectal bleeding since the rectum (the last 15 cm of the colon or large intestine) lies just above the anus. However, the blood could not only originate from the rectum but can also come from other parts of the gastrointestinal system such as the esophagus, stomach, small intestine, and the large intestine.

The color of blood in your stool can indicate where the bleeding occur in your gastrointestinal tract. If your stool has bright red blood, it indicates that the bleeding occur within the anus, rectal area, or the sigmoid colon (part of the large intestine closest to the rectum). On the other hand,  if your stool has black, tarry (sticky), and foul smelling blood, it indicates that the bleeding occur in the upper digestive tract consisting of the right colon, stomach, and the esophagus. The blood turned black and smelly because it stayed long enough in the digestive tract to be acted upon by bacteria. The tarry stool is called melena, produced by bacterial breakdown of blood cells.

Small or mild amount of bright red blood in your stool (a spoon or two) is not dangerous but you should report it to your doctor to get treatment advice. Rectal bleeding becomes dangerous if you pass several bowel movements or a single bowel movement containing a large amount of blood; this can cause a decrease of blood pressure that could lead to a fatal medical shock. If too much blood is lost, blood transfusion is needed immediately.

Below are the causes of bright red blood in stool.

Reasons for Bright Red Blood in Stool

Anal Fissure

Fissure, Image from Wikimedia CommonsAnal fissure is created when the anal lining is torn due to constipation or the forceful movement of  stool in the anus. Tight muscle of the anus can also contribute to the formation of anal fissure. Having anal fissure is painful in subsequent bowel movement. Blood is released through the torn part of the anal lining and can be noticed in the toilet bowl or on the toilet paper as bright red in color. Anal fissure is fairly common and the amount of bleeding is small.


Hemorrhoids are masses or clumps of tissue filled with blood vessels located at the junction of Hemorrhoids, Image from Wikimedia Commonsthe rectum and the anus. People has a notion that having hemorrhoids is an illness but in reality we all have hemorrhoids. Illness occur if the hemorrhoids are enlarged in such a way that they cause bleeding and anal discomfort. Just like anal fissure, the amount of blood lost through hemorrhoids is small and does not cause anemia or low blood pressure.


Diverticulosis, Image from Wikimedia CommonsDiverticulosis is a medical condition in which little sacks or outpocketings (diverticula) develop in the linings of the large intestine. Diverticulosis is common to people at the age of 50-60 and the reason is not entirely known.  It can be due to years of high pressure within the large intestine  or weakness in the colonic wall. Diverticula are more common in the sigmoid colon, a common place of high pressure within the large intestine.

Diverticulosis is not a problem unless the diverticula are ruptured and cause bleeding. Unlike anal fissure and hemorrhoids, bleeding due to a ruptured diverticula can be more severe and brisker. Diverticular bleeding is the most common cause of mild to severe rectal bleeding that needs hospitalization and blood transfusion among aged people in western countries.

Colon Polyps and Cancer

Colon cancer, Image from Wikimedia CommonsPolyps are benign tumors that develops in the wall of the large intestine. Malignant tumors in the colon are called cancer and believed to have developed from the polyps. The amount of blood lost through colon polyps and cancers is small and irregular and typically does not cause a drop in blood pressure or shock. Bright red blood releases through the anus is usually due to bleeding in polyps and cancers located in the rectum or the sigmoid colon.




Like diverticulosis, angiodysplasia is developed in the large intestine of elder population. angiodysplasia, Image from Wikimedia CommonsAngiodysplasia are enlarged blood vessels that frequently occur just under the inner lining of the large intestine. They appear as bright red, spider-like lesions beneath the colon’s lining when observed via colonoscopy. They can develop anywhere in the colon but they are concentrated in the right colon. The cause of angiodysplasia is not yet known but they occur with increasing frequency as people get older. Ruptured angiodysplasia causes bleeding in which bright red, maroon, or dark blood appear in the stools. Anemia symptoms is associated with ruptured angiodysplasia.


Colitis and Proctitis

CD Colitis, Image from Wikimedia CommonsColitis and proctitis are inflammations in the colon and rectum respectively. There are several diseases that causes the colon and rectum to be inflamed. They include ulcerative colitis or proctitis, Crohn’s disease, ischemic colitis, bacterial/viral infection, and radiation colitis or proctitis.

Chron’s disease, ulcerative colitis, and proctitis are chronic inflammatory diseases of the large intestine due to oversensitivity of the body’s immune system to certain substances. Inflammation of the colon causes abdominal pain, diarrhea, and bloody diarrhea. Bleeding can be moderate or severe that medical attention is needed.

Inflammation of the colon due to bacterial or viral infection would have the symptoms of the inflammatory diseases described above. Examples of bacteria that could cause infection are salmonella, shigella, Campylobacter, and E. coli. Cytomegalovirus, on the other hand, is an example of virus that can cause infection.

Meckel’s Diverticulum

Meckel's_Diverticulum, Image from Wikimedia CommonsMeckel’s diverticulum looks like diverticulosis but found in the small intestine near the junction of the small intestine and the large intestine. About 2% of  the population has Meckel’s diverticulum present in the small intestine since birth.  The diverticulum can secrete acid that can cause ulcerations in the inner lining of the diverticulum or nearby tissues. The ulcers created can bleed resulting to the appearance of bright red, dark red, or maroon blood in the stool. Bleeding from a Meckel’s diverticulum, which is painless, is commonly reported among children and young adults.