Bloody Stool – Causes and Other Symptoms

The sight of blood is always a cause for concern even if there are no other symptoms. When it is seen in the stool, even if diarrhea is not present, it can be a very serious sign. Bloody stool should always be medically investigated, especially if it is a recurrent or persistent occurrence.

What is Bloody Stool?

Bloody stool is the presence of blood in stool. Usually it is visible either tainting the toilet water and feces in a red color, or may be evident upon wiping the anus after defecation. Despite the presence of blood, the stool may be normal in color, consistency and frequency. The causes of bloody stool may not always be the same as bloody diarrhea and sometimes the former is more serious.

Signs and Symptoms

Blood stool is a sign of bleeding usually within the lower gastrointestinal tract. It is not a disease on its own, but rather a symptom of some underlying disease. Similarly other signs and symptoms may also be present. However, it is possible for bloody stool to occur on its own without any other signs or symptoms.

Bloody Red Stool vs Tarry Dark Stool

The color of the bloody stool can be helpful in identifying the location of the bleed. If the blood is red, bright and appears ‘fresh’ then the bleed is more likely in the lower gut, such as within the colon, rectum or anus. If the stool appears dark, even black, and tarry then the bleeding is more likely from higher up in the gut, such as the small intestines of stomach. Read more on fresh blood or dark blood in the stool.

Even fresh red blood in the stool may not always be visible to the naked eye. Most of the time blood in the stool is not visible and is detected by fecal occult blood test (FOBT). This is known as microscopic bleeding. However, there are cases where the blood loss is so significant that it is easily visible in the stool and may even stain the toilet water. This is referred to as gross bleeding.

Other Symptoms

The following signs and symptoms may be present:

Generalized/systemic symptoms may also be present such as fever, unintentional weight loss, change in appetite and fatigue.

Causes of Bloody Stool

Most of the upper gastrointestinal causes of blood stool usually leads to dark tarry stools, also known as melena. Here the stools appear darker in color and sometimes even black. Red blood stools is due to lower gastrointestinal tract and these conditions are discussed in further detail. Infections in the bowel that may lead to bleeding usually present with diarrhea and not stool of normal consistency and frequency.


Trauma to the rectum and anus can lead to bleeding which may then present as bloody stool. It can occur with physical, chemical or electromagnetic trauma. These injuries may be seen with anal intercourse, colonoscopy that is not done properly, excessive scratching of the anus and radiation exposure.


This is one of the most common causes of bloody stool. Hemorrhoids (piles) is where veins the rectum and around the anus becomes swollen, inflamed and tortuous. It may bleed and this is mainly seen as blood upon wiping after having a bowel movement or bloody stool.


Hard and sometimes large stools that are eventually passed out in constipated people can injure the anus. This may lead to bleeding. The straining can also cause hemorrhoids and aggravate it which may then contribute to bloody stool. Similarly on the other end of the spectrum, diarrhea can lead to and exacerbate hemorrhoids.

Anal Fissures

Anal fissures are where tiny tears occur on the lining of the anus. This may result in bleeding. These tears are often associated with injury to the anus but can also occur with infections and other inflammatory diseases. Most cases are minor and may cause discomfort but not significant bleeding. However, in severe cases there may be bloody stool.

Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic autoimmune condition affecting the bowels leading to inflammation and often ulceration within the gut wall. The colon is usually affected and the IBD lesions may bleed. This can cause bloody stool and may also be accompanied by mucus in the stool.


Colorectal cancer is one of the common malignancies and one of the symptoms is bloody stool. Anal cancer may also present with blood stool but this is not a common type of cancer. Bleeding is not always an early symptom of these cancers and may only be seen after other symptoms arise.

Rectal Prolapse

Rectal prolapse is a condition where a portion of the rectum protrudes through the anus. Sometimes the veins within the rectum (internal hemorrhoids) may protrude but in other cases even the rectal wall is bulging through the anus. Bleeding may occur from the protruding portion of the rectal wall.


Diverticula is where abnormal pouches form in the wall of the colon. This is mainly seen in the elderly and people who are constipated. When these pouches get infected, the condition is known as diverticulitis. It may cause diarrhea, abdominal pain and abnormal urging to defecate. There may also be blood in the stool.

Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) does not present with the same inflammation and ulcers of the bowel wall like inflammatory bowel disease (IBD). The condition itself does not directly lead to bleeding from anywhere in the gut. However, the diarrhea or constipation in IBS may lead to conditions like hemorrhoids which can cause bloody stool.

Foods and Beverages

Sometimes the presence of a red color in the stool may not be due to bleeding. Instead it may arise from certain foods and beverages that were recently consumed. This is usually seen with foods or beverages that have strong red artificial dyes but can also occur with certain natural pigments in specific foods or drinks.

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