Call Us

Contact Us

Blood in Stools: Is It Always a Sign of Colon Cancer?

woman with cancer written on her stomach

Finding blood in stools can be alarming and often raises concerns about serious health issues, such as colon cancer. However, blood in stools can be caused by a variety of conditions, not all of which are life-threatening. 

This article explores the possible causes of blood in stools, how to differentiate between them, and when to seek medical advice, emphasizing that while colon cancer is a significant concern, it is not the only potential cause.

What Is Blood in Stools?

Blood in stools, also known as rectal bleeding, can manifest in several ways. It may appear as bright red blood on toilet paper or in the toilet bowl, maroon-colored stools, or black, tarry stools (melena). The color and consistency of the blood can provide clues about its source within the gastrointestinal (GI) tract.

Common Causes of Blood in Stools

There are many potential causes of blood in stools, ranging from minor to severe conditions. Understanding these can help alleviate unnecessary anxiety and prompt timely medical intervention when needed.


Hemorrhoids are swollen blood vessels in the rectum or anus that can cause bright red blood in stools. They are often associated with straining during bowel movements, constipation, or prolonged sitting in the commode. Hemorrhoids can be painful or itchy but are generally not life-threatening.

Anal Fissures

Anal fissures are small tears in the lining of the anus, often caused by passing hard stools or straining. These can cause sharp pain and bright red blood on the toilet paper or surface of stools. Like hemorrhoids, fissures are usually benign and can often be treated with dietary changes and topical treatments including sitz baths.

Diverticulosis and Diverticulitis

Diverticulosis involves the formation of small pouches (diverticula) in the colon wall. These pouches can sometimes bleed, leading to blood in stools. When these pouches become inflamed or infected, the condition is known as diverticulitis, which can cause more significant bleeding, pain, and fever.

Gastrointestinal Infections

Infections caused by bacteria, viruses, or parasites can lead to inflammation and bleeding in the GI tract. Symptoms often include diarrhea, abdominal pain, and fever, along with blood in stools. Common culprits include E. coli, Salmonella, and Campylobacter. These can be life-threatening when severe dehydration occurs. 

Inflammatory Bowel Disease (IBD)

IBD, including Crohn’s disease and ulcerative colitis, involves chronic inflammation of the digestive tract. Both conditions can cause blood in stools, often accompanied by abdominal pain, diarrhea, weight loss, and fatigue. IBD requires ongoing medical management to control symptoms and prevent complications such as colorectal cancer.

Polyps and Colon Cancer

Colon polyps are growths on the inner lining of the colon that can bleed. While most polyps are benign, some can develop into colon cancer over time. Colon cancer itself can cause blood in stools, which may be bright red or dark, depending on the location of the tumor. Other symptoms can include changes in bowel habits, unexplained weight loss, and abdominal pain.

Differentiating Causes of Blood in Stools

Symptoms and Characteristics

The characteristics of the blood and accompanying symptoms can help differentiate between various causes:

  • Bright Red Blood: Often indicates bleeding from the lower GI tract, such as hemorrhoids, anal fissures, or diverticulosis.
  • Dark, Tarry Stools (Melena): Suggests bleeding from the upper GI tract, such as from a stomach ulcer or gastritis.
  • Maroon-Colored Stools: May indicate bleeding from the middle section of the GI tract, including the small intestine or right colon.

When to Seek Medical Attention

Any instance of blood in stools should prompt medical evaluation to determine the underlying cause. However, certain symptoms warrant more immediate attention:

  • Large Amounts of Blood: Significant bleeding can lead to anemia and low blood pressure,indicating a severe underlying condition.
  • Persistent Bleeding: Ongoing blood in stools requires investigation to identify and address the cause.
  • Associated Symptoms: Severe abdominal pain, weight loss, changes in bowel habits, and fatigue alongside blood in stools may indicate a serious condition like colon cancer or IBD.

Diagnostic Procedures

Medical History and Physical Examination

Your healthcare provider will start with a thorough medical history and physical examination. They will ask about the frequency, color, and amount of blood, as well as any associated symptoms.

Diagnostic Tests

To pinpoint the cause of blood in stools, various diagnostic tests may be conducted:

  • Stool Tests: To check for infections, inflammation, or hidden blood.
  • Blood Tests: To assess overall health and detect anemia or signs of infection.
  • Endoscopy: Procedures like colonoscopy or sigmoidoscopy allow direct visualization of the colon and rectum to identify sources of bleeding.
  • Imaging Studies: CT scans or MRI may be used to evaluate the abdominal organs and detect abnormalities.

Treatment Options

Addressing the Underlying Cause

Treatment for blood in stools focuses on addressing the underlying cause:

  • Hemorrhoids and Anal Fissures: Increasing dietary fiber, using topical treatments, and taking sitz baths can alleviate symptoms.
  • Diverticulosis: Dietary changes and, in the case of diverticulitis, antibiotics or surgery may be required.
  • Infections: Antibiotics or antiparasitic medications are prescribed based on the type of infection.
  • IBD: Medications to reduce inflammation and manage symptoms are essential.
  • Polyps and Colon Cancer: Polyps may be removed during colonoscopy, while cancer treatment typically involves surgery, chemotherapy, or radiation therapy.

Preventive Measures

Preventive measures can reduce the risk of conditions that cause blood in stools:

  • Diet and Lifestyle: A diet rich in fiber, regular exercise, and staying hydrated promote healthy bowel movements.
  • Regular Screenings: Colonoscopy screenings, especially for those over 50 or with a family history of colon cancer, help detect and remove polyps early.
  • Medication Management: For those with chronic conditions like IBD, adhering to prescribed treatments is crucial.


Blood in stools is a symptom that should never be ignored, but it is not always a sign of colon cancer. Understanding the various causes and knowing when to seek medical attention can help ensure timely and appropriate treatment. If you experience blood in your stools, consult with your healthcare provider to determine the cause and receive the necessary care.


Introducing Curasia Endoscopy Centre

Our host, Jerald Foo, will be taking you to our first centre at Jurong East.

Make An Enquiry

Leave us your details and we’ll get back to you shortly.
Prefer to talk? Call our clinic directly to make an enquiry at +65 6679 1229

or Whatsapp us at +65 9750 8783

We are available 24 hours

Let's Get in Touch!

Clinic Details

Other Related Articles

Curasia Endoscopy

Call Us

Contact Us