Is My Stool Test Accurate If I Didn't Collect a Full Sample?

Recent rectal bleeding has been observed. If the stool sample collected for screening did not include the entire stool, could this affect the accuracy of the screening?

Hello, since only my mother passed away from colon cancer in our family, I recently went to the hospital for a health check-up, including a stool screening.
I only scraped a bit of stool from the surface, but I've been experiencing pain during bowel movements lately, and I've noticed blood when wiping, although there is no blood in the stool itself.
I've had similar issues in the past, but they weren't persistent.
Recently, it has occurred about once every two to three months.
Should I go for another stool screening, or should I wait for the results of this screening first?

Jun Jun, 30~39 year old female. Ask Date: 2022/08/02

Dr. Ke Fangxu reply Surgery

The likelihood of developing colon cancer at the age of 33 is not zero, but generally speaking, it is very low.
Based on your description, it seems more like hemorrhoidal bleeding.
I recommend starting with a light diet and maintaining a good lifestyle.
Spicy, irritating, and greasy foods should be avoided, and increasing dietary fiber can also be helpful.
If symptoms persist without improvement, you may want to consult a physician for medication or to undergo a colonoscopy.
However, it would be best to wait for the results of the stool test before proceeding further.

Reply Date: 2022/08/02

More Info

When it comes to stool tests, particularly those designed to detect hidden blood (fecal occult blood tests), the accuracy of the results can indeed be influenced by how the sample is collected. In your case, if you did not collect a full sample, there are several factors to consider regarding the reliability of the test results.

Firstly, the fecal occult blood test is designed to detect small amounts of blood in the stool, which can be an early sign of conditions such as colorectal cancer or polyps. The test is generally more accurate when a complete and representative sample is collected. If you only scraped a small portion of the stool, it may not provide a comprehensive view of what is happening in your gastrointestinal tract. This is particularly important given your family history of colorectal cancer, which increases your risk.

Additionally, you mentioned experiencing pain during bowel movements and noticing blood when wiping, although not in the stool itself. These symptoms could indicate several conditions, including hemorrhoids, anal fissures, or other gastrointestinal issues. While these conditions are often benign, they can also be associated with more serious issues, especially in someone with a family history of colorectal cancer.

Given these factors, it would be prudent to consider retesting. If the initial test results come back negative but you continue to experience symptoms such as pain and bleeding, it is essential to follow up with your healthcare provider. They may recommend further diagnostic procedures, such as a colonoscopy, to investigate the source of your symptoms more thoroughly.

In summary, while the fecal occult blood test can provide valuable information, the accuracy of the results can be compromised if the sample is not collected properly. Given your symptoms and family history, it would be wise to discuss your concerns with your doctor and consider retesting or further evaluation, regardless of the initial test results. Early detection is crucial in managing potential gastrointestinal issues, especially with a family history of colorectal cancer. Always prioritize your health and seek professional advice when in doubt.

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