Fecal Occult Blood Test - A Review

Introduction

The fecal occult blood test is an important screening tool for identifying gastrointestinal bleeding, even when it is not visible to the unaided eye. It is an economical, non-invasive technique used in hospitals and clinics to detect serious conditions like colorectal cancer and other gastrointestinal diseases. This article intends to explore this procedure, its types, methods, interpretation, advantages, and limitations.

What Is the Fecal Occult Blood Test?

The fecal occult blood test, also known as stool guaiac test, is a diagnostic process used to find hidden or occult blood in feces. Blood that is not readily visible in the feces but can be identified through laboratory testing is called occult blood. Occult blood, if present in feces, could be a sign of underlying gastrointestinal disorders like polyps, hemorrhoids, ulcers, inflammatory bowel diseases, or even cancer of the colon.

What Are the Types of Fecal Occult Blood Tests?

• Guaiac Fecal Occult Blood Test: This traditional method involves treating a stool sample with the chemical reagent guaiac. Guaiac is a plant-derived substance whose chemical reacts with the heme component of hemoglobin to change blood color. Its use has been limited because of its poor specificity and sensitivity. Diet factors like red meat and certain fruits and vegetables are affected. Also, consumption of certain medications, like nonsteroidal anti-inflammatory drugs, might affect the results, leading to more false positive results.

• Immunochemical Fecal Occult Blood Test: With the help of antibodies, this test has the potential to detect human hemoglobin when compared with the traditional method specifically. Therefore, this method has improved sensitivity and specificity and is the more recommended approach to screening colorectal cancer. Furthermore, it eliminates dietary restrictions and false positives caused by particular foods or medications.

What Is the Procedure Involved?

The following steps are usually involved in the process of doing a fecal occult blood test:

• Stool Sample Collection: Patients receive a collection kit that includes a unique container and instructions on how to take a tiny sample of their feces (stool).

• Sample Preparation: Patients may need to adhere to particular guidelines, such as refraining from eating or taking certain medications, depending on the type of fecal blood test used.

• Test Application: A small stool sample is placed on a test card containing guaiac reagent for the traditional method. The sample must be placed in a collecting tube that comes with the test kit for the immunochemical test.

• Laboratory Analysis: After the sample is ready, it is delivered to a lab for examination. Using the proper technique, technicians look for occult blood in the sample.

How to Interpret the Results?

It is very important to distinguish the true positives from false positives and negatives carefully. Positive results suggest that there may be occult blood in the stool, which calls for additional testing to determine the underlying cause, like a colonoscopy. When the test results come back positive, it is important to remember that they do not always indicate the presence of colorectal cancer; rather, they are a sign that more investigations are necessary.

What Is the Clinical Importance of this Test?

The fecal blood test is a clinically important test for screening colorectal cancer and other gastrointestinal disorders. By using this test to detect disorders, especially cancers, early, prompt interventions may improve patient outcomes and significantly lower death rates. Additionally, routine fecal occult blood test screening can assist in identifying precancerous lesions like polyps, enabling their removal before the development of full cancer.

What Are the Advantages and Limitations of the Fecal Occult Blood Test?

The main advantages include:

• Noninvasive: No specialized equipment or medical supervision is needed. It is a non-invasive procedure that can be carried out at home. This helps individuals reluctant to participate in more screening tests and helps in early detection.

• Reduced Anxiety: The test has a relatively less stressful experience than other invasive tests. This also leads to a higher compliance rate amongst patients for the testing.

• Cost Effectiveness: The fecal occult blood test is more affordable than other invasive diagnostic procedures, such as colonoscopies, making it more accessible to a broader population.

• Early Detection: A fecal occult blood test can identify colorectal cancer and other gastrointestinal disorders earlier, making initiating prompt treatment easier and achieving better results.

• Convenience: Thanks to at-home fecal occult blood test kits, people can easily collect stool samples and undergo screening without visiting a healthcare facility.

• Preventive Health Awareness: Routine testing using this test helps prevent diseases and detect them early. Once detected, treatment can be initiated immediately. This makes the person more aware of their health status from a public health view.

The limitations include:

• Sensitivity and Specificity: Compared to immunochemical techniques, the traditional fecal occult blood test has lower sensitivity and specificity, increasing false positives and negatives. False positives lead to unnecessary patient worry and an increase in treatment costs.

• Dietary Restrictions: To lower the possibility of false positives, traditional fecal occult blood tests, patients must follow certain dietary guidelines, such as avoiding red meat and particular fruits and vegetables.

• Single-time Detection: Because the fecal occult blood test is a single-time detection technique, it might not be able to identify tiny lesions or sporadic bleeding. Test results that are positive for the fecal occult blood test require further testing, usually using a colonoscopy. This can result in extra expenses and inconvenience for the patients.

• Limited Ability: Certain upper gastrointestinal bleeding might go undetected in this test, leading to delays in treatment.

Conclusion

To conclude, the fecal occult blood test is essential for both the screening of colorectal cancer and the identification of other gastrointestinal illnesses. With advancements in immunochemical techniques, fecal occult blood tests are more patient-friendly, precise, and sensitive. It is best performed with other comprehensive screening tests like colonoscopy to be effective. Also, careful consideration must be given while interpreting its results. Healthcare professionals can support early detection, prompt intervention, and better outcomes for those at risk of colorectal cancer and gastrointestinal disorders by encouraging routine fecal occult blood test screening.