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What Does Blood in the Stools Indicate?

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Discovering blood in the stools can be a concerning and alarming experience. While it is essential not to panic, it is equally crucial to take blood in stools seriously as it can be a sign of an underlying medical condition. This article will delve into the various causes of blood in stools, the significance of this symptom, and when it is advisable to seek medical attention.

Blood in Stools Defined

Blood in stools, also known as rectal bleeding or hematochezia, refers to the passage of blood when having a bowel movement. The blood may appear bright red, maroon, or even black, depending on its source and how long it has been in the digestive tract

Types of Blood in Stools

Blood in stools can manifest in two primary forms:

  • Visible Blood: This is when blood is readily apparent in the stool or on toilet paper.
  • Occult Blood: Occult or hidden blood cannot be seen with the naked eye and often requires specialized tests, such as a fecal occult blood test (FOBT), for detection.

Common Causes of Blood in Stools

Several factors can contribute to blood in stools. These causes range from benign and self-limiting conditions to more serious medical issues. It is essential to understand that rectal bleeding is a symptom, not a diagnosis, and its underlying cause should be evaluated by a healthcare provider.


Hemorrhoids are one of the most common causes of bright red blood in stools. They are swollen rectal tissues with enlarged blood vessels and can bleed during bowel movements. Hemorrhoid-related bleeding is typically painless.

Anal Fissures

Anal fissures are small tears or cracks in the lining of the anus, often caused by straining during bowel movements or passing hard stools. They can lead to bleeding during and after defecation and are very painful.

Gastrointestinal Bleeding

Gastrointestinal bleeding can occur at various points in the digestive tract and present as blood in stools. This bleeding may result from:

  • Gastric Ulcers. Open sores in the stomach lining can cause bleeding, leading to the presence of hematochezia (blood in stools) or tarry stools known as melena.
  • Esophageal Varices. Enlarged veins in the esophagus, often associated with liver disease, can lead to severe bleeding, resulting in hematochezia or melena.
  • Mallory-Weiss Tears. Tears in the lining of the esophagus due to severe vomiting can lead to hematochezia.
  • Diverticulosis. Small pouches (diverticula) in the colon can bleed if they become inflamed or rupture.
  • Inflammatory Bowel Disease (IBD). Conditions like Crohn’s disease and ulcerative colitis can cause chronic inflammation in the digestive tract, leading to bleeding at various points along the tract.
  • Colon Polyps and Cancer. Benign growths (polyps) or colorectal cancer can cause bleeding within the colon or rectum.

Anal Conditions

Various anal conditions, including rectal or anal cancer, can cause blood in stools. These conditions may be associated with additional symptoms like changes in bowel habits or weight loss.

Medications and Dietary Factors

Certain medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs) and blood thinners, can contribute to gastrointestinal bleeding and rectal bleeding. Additionally, excessive consumption of spicy foods or alcohol may irritate the digestive tract and lead to temporary bleeding.

Infectious Causes

Infections in the gastrointestinal tract, such as bacterial, viral, or parasitic infections, can result in inflammation and bleeding. Conditions like gastroenteritis or infections with pathogens like Clostridium difficile (C. diff) may cause blood in stools.

Interpreting Blood in Stools

Depending on the site of bleeding, blood presents differently. When coming from higher up the digestive tract (before digestive contents solidify to form stools), the blood is more likely to be mixed within stools or be a composite of it, and not merely coating it. The interpretation of blood in stools depends on various factors, including the color of the blood, the patient’s medical history, associated symptoms, and diagnostic findings:

  • Bright Red Blood in Stools. Bright red blood in stools is often associated with conditions closer to the anus or rectum, such as hemorrhoids or anal fissures. It can also result from bleeding in the lower colon or rectum, potentially due to diverticulosis or inflammatory bowel disease.
  • Dark or Tarry Stools (Melena). Black, tarry stools (melena) often indicate upper gastrointestinal bleeding, typically from the stomach or upper small intestine. The slow passage of blood down the digestive tract allows iron in blood to be oxidized, lending to the dark colour of stools. Conditions such as gastric ulcers, esophageal varices, or Mallory-Weiss tears can lead to melena.
  • Occult Blood in Stools. Occult blood in stools, which cannot be seen with the naked eye, may still indicate underlying gastrointestinal bleeding. Occult blood testing is often used as a screening tool, especially for colorectal cancer.
  • Mixed Blood and Stool. The presence of blood mixed with stools can suggest bleeding higher up in the large intestine. It may be seen in conditions like diverticulosis with diverticular bleeding or colorectal cancer with tumor bleeding.
  • Clots or Mucus in Stools. The presence of clots or mucus in stools can sometimes accompany blood in stools and may indicate more severe bleeding. It is essential to promptly seek medical attention if these symptoms occur.

When to Seek Medical Attention

Rectal bleeding, especially if it is recurrent, persistent, or accompanied by other concerning symptoms, should prompt individuals to seek medical attention:

  • First Episode of Rectal Bleeding. 
If you experience rectal bleeding for the first time, it is advisable to consult a healthcare provider to determine its cause.
  • Persistent or Recurrent Bleeding. Rectal bleeding that persists or recurs over time should not be ignored. This could indicate an ongoing issue that requires evaluation.
  • Significant Blood Loss. 
Experiencing a large amount of blood in stools, feeling lightheaded, dizzy, or fatigued, or having a rapid heart rate can be signs of significant blood loss and require immediate medical attention.
  • Changes in Bowel Habits. 
Rectal bleeding accompanied by changes in bowel habits, such as diarrhea or constipation, may indicate an underlying condition that needs evaluation.
  • Abdominal Pain or Cramping. 
If rectal bleeding is associated with abdominal pain or cramping, it may indicate a more complex issue that warrants investigation.
  • Weight Loss or Anemia. 
Unexplained weight loss or the development of anemia (low hemoglobin levels) in association with rectal bleeding should be evaluated for underlying causes.
  • Age and Risk Factors. Individuals over the age of 50 or those with a family history of colorectal cancer should prioritize colorectal cancer screening if they experience rectal bleeding or other concerning symptoms.


Blood in stools, whether it appears as bright red blood, dark and tarry stools, or is detected through occult blood testing, is a symptom that can indicate various underlying medical conditions. While some causes of rectal bleeding may be benign and self-limiting, others can be serious and require prompt medical evaluation and treatment.

It is crucial not to ignore rectal bleeding, especially if it is recurrent, persistent, or associated with other concerning symptoms. Seeking medical attention, undergoing diagnostic tests, and receiving a proper diagnosis are essential steps in identifying and addressing the underlying cause of blood in stools. Early detection and intervention can significantly impact the outcome and prognosis of conditions that may be contributing to rectal bleeding.

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