Blood in Stool: Causes, Symptoms, and Diagnosis

Blood in stool, medically referred to as hematochezia or melena, is a symptom that can cause significant concern. However, it's important to understand that while this symptom can sometimes indicate serious health conditions, it can also be caused by relatively benign issues. This article aims to provide a comprehensive understanding of the causes, symptoms, and diagnostic procedures related to the presence of blood in the stool.

What is Blood in Stool?

Blood in the stool can be visibly apparent or only detectable through microscopic examination or laboratory tests. This latter case is often referred to as occult blood in the stool.

When the bleeding originates from the rectum or anus, it may result in bright red streaks of blood on toilet paper or in the toilet bowl. Dark stools can indicate bleeding from the initial sections of the intestines, as the blood gets digested and changes color.

Causes of Blood in Stool

The presence of blood in the stool can be attributed to a variety of conditions, ranging from common to rare.

Common Causes

  1. Hemorrhoids and Anal Fissures: These are two of the most common causes of blood in the stool. Hemorrhoids are swollen blood vessels in the rectum or anus that can be internal or external. Anal fissures are small tears in the lining of the anus.

  2. Gastrointestinal Conditions: Conditions like ulcerative colitis, Crohn's disease, and diverticulosis can cause blood in the stool. These conditions cause inflammation in different parts of the digestive tract.

  3. Polyps or Colorectal Cancer: Intestinal polyps are noncancerous growths on the lining of the colon or rectum. However, some polyps can become cancerous over time. Colorectal cancer is a serious condition that can cause blood in the stool, especially in its advanced stages.

Rare Causes

  1. Infectious Diseases: Certain infections, such as amoebiasis, shigellosis, and salmonella, can cause bloody stools.

  2. Other Conditions: Conditions like liver cirrhosis, kidney failure, and peptic ulcers can also result in blood in the stool.

Symptoms and Diagnosis

In addition to visible blood, other symptoms may accompany this condition such as changes in bowel movements, unexplained weight loss, or unusual fatigue. These symptoms may indicate serious conditions like colorectal cancer. However, these symptoms often appear only when the disease is in an advanced stage, emphasizing the importance of regular screening tests.

To diagnose the cause of blood in the stool, healthcare professionals may use various methods. A colonoscopy is a common procedure used to examine the colon and rectum. Stool tests can detect occult blood, and other imaging tests can provide a detailed view of the digestive tract.


While the presence of blood in the stool can be alarming, it's important to remember that it's not always indicative of a serious condition. However, it should never be ignored, and medical advice should be sought to determine the cause and appropriate treatment. Regular screening and early detection are crucial in managing many of the conditions that cause blood in the stool.

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