How to check fecal occult blood

Fecal occult blood test is usually performed through fecal occult blood test, which is an important method for screening gastrointestinal bleeding. There are mainly detection methods such as chemical method, immunological method, and transferrin method.

1. Chemical method:

The chemical method utilizes the peroxidase like activity of hemoglobin to make the reagent color to determine the result. Easy to operate, low cost, commonly used for preliminary screening. However, this method is susceptible to dietary interference, such as consuming animal blood, red meat, iron rich vegetables, or medications, which may lead to false positive results. Usually, the above-mentioned foods need to be restricted for 3 days before inspection. If the result is positive, it suggests that there may be a small amount of gastrointestinal bleeding and further investigation is needed.

2. Immunoassay:

Immunoassay uses specific antibodies to detect human hemoglobin, which is currently the more commonly used method in clinical practice. It is not affected by animal hemoglobin or plant peroxidase in food, has high specificity, and is particularly suitable for early screening of colorectal cancer. During operation, a dedicated sampling rod is usually used to collect a small amount of fecal samples, which are then placed in buffer solution for testing. Immunotherapy is more sensitive to lower gastrointestinal bleeding, but hemoglobin may be degraded by digestive enzymes during upper gastrointestinal bleeding, leading to false negatives.

3. Transferrin method: The combination of

transferrin method and fecal transferrin detection can compensate for the shortcomings of immune method in detecting upper gastrointestinal bleeding. Transferrin has good stability in the intestine and is not easily destroyed by digestive enzymes, so it can more comprehensively reflect the situation of gastrointestinal bleeding. This method is often used in combination with immunological methods to improve the sensitivity and accuracy of detection, especially suitable for screening for occult gastrointestinal bleeding of unknown causes.

4. Quantitative detection method:

The quantitative detection method accurately measures the concentration of hemoglobin in feces through automated instruments, and the results are presented in numerical form, which can dynamically monitor changes in bleeding volume. This method avoids subjective interpretation errors and is suitable for patients who require regular follow-up, such as those after colorectal cancer surgery or inflammatory bowel disease treatment. Quantitative testing can distinguish between minor bleeding and significant bleeding, providing more refined basis for clinical decision-making.

5. Home self testing method:

The home self testing method uses commercially available fecal occult blood test strips or detection cards, and samples and reads according to the instructions. Easy to operate, suitable for people who are unwilling to seek frequent medical treatment or require long-term monitoring. However, the sensitivity and specificity of home testing are lower than those of hospital laboratory testing, and the results are affected by factors such as sampling methods and interpretation time. If the self-test is positive, it is recommended to seek medical attention promptly for standardized colonoscopy and other examinations to determine the cause. Before conducting a fecal occult blood test, it is recommended to maintain a normal diet and avoid consuming large amounts of red meat, animal blood, or iron supplements to avoid interfering with the results. During the inspection, use a clean container to collect fresh fecal samples and avoid mixing them with urine or water. If the results are abnormal, a comprehensive evaluation should be conducted in combination with gastrointestinal endoscopy, imaging, and other examinations, and dietary and lifestyle adjustments should be made according to medical advice, such as increasing dietary fiber intake and maintaining regular bowel movements, which can help maintain digestive health.