Should You Get a Colonoscopy After Positive Fecal Occult Blood Test?

Fecal occult blood issue?

If the fecal occult blood test results are positive for both chemical and immunological methods, is it recommended to proceed with a colonoscopy or to repeat the occult blood test?

Sen Sen, 10~19 year old female. Ask Date: 2015/12/23

Dr. Ke Fangxu reply Surgery

A positive fecal occult blood test indicates the presence of blood in the stool, thus further investigation is necessary to identify the source of the bleeding.
According to the recommendations of the American Gastroenterological Association, it is advised to conduct three consecutive fecal occult blood tests over three days.
If any one of these tests returns a positive result, a colonoscopy should be performed to rule out the possibility of a false negative leading to a missed diagnosis.
However, the National Health Administration's colorectal cancer screening program only covers one test.
Consequently, if this single test is positive, a colonoscopy is required; otherwise, why would one trust a negative result as accurate while deeming a positive result as incorrect? After all, the purpose of the occult blood test is screening, and it is more reasonable to eliminate the possibility of false negatives rather than to disregard the implications of false positives.

Reply Date: 2015/12/23

More Info

When faced with a positive fecal occult blood test (FOBT), whether it’s through chemical or immunological methods, it is generally advisable to proceed with a colonoscopy. A positive result indicates that there is blood in the stool, which can be a sign of various conditions, ranging from benign issues to more serious concerns such as colorectal cancer.
The fecal occult blood test is a screening tool used to detect hidden (occult) blood in the stool. While a positive result can be alarming, it is important to understand that it does not definitively indicate cancer or any specific disease. There are several potential causes for a positive FOBT, including:
1. Hemorrhoids: These are swollen blood vessels in the rectum or anus that can bleed, leading to a positive test result.

2. Diverticular Disease: Small pouches in the colon can become inflamed or infected, causing bleeding.

3. Gastrointestinal Infections: Certain infections can lead to inflammation and bleeding in the gastrointestinal tract.

4. Polyps: Non-cancerous growths in the colon can bleed and may be precursors to cancer.

5. Colorectal Cancer: This is the most serious concern associated with a positive FOBT, and it is why further investigation is warranted.

Given the potential for serious underlying conditions, a colonoscopy is often recommended following a positive FOBT. This procedure allows for direct visualization of the colon and rectum, and it provides the opportunity to take biopsies or remove polyps if necessary.
In some cases, healthcare providers may suggest repeating the FOBT before proceeding to a colonoscopy, especially if the initial positive result was borderline or if there are no other concerning symptoms. However, if both the chemical and immunological tests are positive, it is generally prudent to proceed with a colonoscopy without delay.
Additionally, if you are experiencing symptoms such as changes in bowel habits, abdominal pain, or blood in the stool, these are further indicators that a colonoscopy is warranted. Symptoms like these can provide additional context to the test results and help guide the urgency of further evaluation.

In summary, if both the chemical and immunological fecal occult blood tests are positive, it is advisable to undergo a colonoscopy. This procedure is a critical step in determining the cause of the bleeding and ruling out serious conditions such as colorectal cancer. It is always best to discuss your specific situation with your healthcare provider, who can provide personalized recommendations based on your medical history and current symptoms.

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