Positive Fecal Occult Blood Test Results: Key Concerns

Positive fecal occult blood test issue?

Hello Dr.
Ke,
I am Ah-Jie.
I have a habit of exercising and consuming fruits and vegetables regularly, but I still experience constipation.
Therefore, I have been taking the following medications for a long time: magnesium oxide, motility agents (such as domperidone), and Laxative granules (fiber supplements).
I am concerned about the risk of constipation leading to colorectal issues.
Two years ago, I underwent a colonoscopy, and the results were normal, although I was diagnosed with internal hemorrhoids.
Last month, I had a health check-up, and the fecal occult blood test (immunochemical type) returned a positive result of 25 ng/ml (the hospital's standard is 12 ng/ml).
I am quite worried and have the following questions for you:
1.
Occasionally, after a bowel movement, I experience a sharp pain in my anus.
Could this be a sign of anal fissure?
2.
On the day I collected the stool sample, my stool was quite thick (about the width of two fingers), with the front part being hard and the end part having a normal consistency.
I collected the sample from the end of the stool.
If I have an anal fissure, could it cause a slightly elevated positive reaction? (I read online that if there are hemorrhoids or anal fissures, the fecal occult blood test results can be in the hundreds ng/ml.)
3.
Since I had a colonoscopy two years ago with no abnormalities, is it possible for colorectal cancer to develop within two years?
4.
Could long-term use of magnesium oxide, motility agents, and Laxative granules increase the risk of gastrointestinal cancer?
5.
Should I undergo another colonoscopy, or should I consider both a colonoscopy and an upper gastrointestinal endoscopy?
I apologize for asking you so many questions, and I greatly appreciate your time in reading and responding.
Best regards,
Ah-Jie

A-Jie, 30~39 year old female. Ask Date: 2016/12/01

Dr. Ke Fangxu reply Surgery

1.
It is necessary to confirm the diagnosis through a physician's examination.

2.
There may be a direct correlation between the values presented by the immunological test and the amount of bleeding; if the bleeding is minimal, it is possible to obtain lower values.

3.
It is unlikely, as the development of colorectal cancer typically takes time; however, one cannot completely rule out the possibility of a small malignant lesion developing within two years.

4.
Over-the-counter laxatives are not associated with cancer risk, but products claiming to be enzymes without proper certification cannot be guaranteed safe.

5.
It should not be necessary, but if there are lingering concerns, repeating the test would not hurt.

Reply Date: 2016/12/01

More Info

Dear Ah-Jie,
Thank you for reaching out with your concerns regarding your recent positive fecal occult blood test (FOBT) results. It's understandable to feel anxious, especially given your history of constipation and the measures you've taken to manage it. Let's address your questions one by one.

1. Anal Pain and Possible Anal Fissures: The pain you experience after bowel movements could indeed be indicative of an anal fissure, especially if it is sharp and occurs during or after passing a stool. Anal fissures are small tears in the lining of the anus, often caused by passing hard or large stools. They can lead to significant discomfort and may cause bleeding, which could potentially contribute to a positive FOBT result.

2. Stool Characteristics and FOBT Results: The texture and consistency of your stool can influence the results of the FOBT. If you had a hard stool that caused trauma to the anal area, it could lead to minor bleeding, resulting in a positive test. However, significant bleeding from hemorrhoids or fissures typically results in much higher levels of blood in the stool. Your reported level of 25 ng/ml, while above the threshold, is not excessively high, which may suggest that the source of bleeding is not severe.

3. Risk of Colorectal Cancer: While it is possible for colorectal cancer to develop within two years, especially if there are risk factors present, the likelihood is generally low if your previous colonoscopy was normal. However, the presence of a positive FOBT warrants further investigation, as it can indicate other conditions, including polyps or other benign issues.

4. Long-term Use of Laxatives and Fiber Supplements: The medications you are taking, such as magnesium oxide and fiber supplements, are generally safe and do not inherently increase the risk of colorectal cancer. However, chronic constipation and the need for laxatives can sometimes be associated with underlying gastrointestinal issues. It's essential to monitor your bowel habits and discuss any significant changes with your healthcare provider.

5. Need for Repeat Colonoscopy: Given your positive FOBT result, it is advisable to follow up with a colonoscopy, even if your previous one was normal. This is especially important to rule out any potential issues that may have developed since your last examination. A colonoscopy can provide a direct view of the colon and allow for biopsies if necessary. Depending on your symptoms and risk factors, your doctor may also recommend an upper endoscopy (esophagogastroduodenoscopy, or EGD) to evaluate your upper gastrointestinal tract.

In conclusion, while a positive FOBT can be alarming, it is essential to approach it with a thorough evaluation rather than immediate panic. The combination of your symptoms, medication history, and the FOBT result suggests that further investigation is warranted. I recommend scheduling an appointment with your healthcare provider to discuss your symptoms and the need for a colonoscopy. They can provide personalized advice and ensure that you receive the appropriate care.

Take care, and I hope this information helps alleviate some of your concerns.

Best regards,
Doctor Q&A Teams

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