Fecal Occult Blood Test (ELISA)
The fecal occult blood test (detecting hidden gastrointestinal bleeding) using immunochemical methods is a modern, sensitive, and specific laboratory test based on detecting human hemoglobin and transferrin in stool samples by antibodies.
- Principle of the method:
ELISA (enzyme-linked immunosorbent assay) uses specific antibodies that bind human hemoglobin or transferrin, allowing qualitative and quantitative determination of blood presence in stool. The method relies on the antigen–antibody reaction with an enzyme label producing a measurable color signal.
- Advantages of immunochemical analysis:
- Higher sensitivity and specificity compared to traditional chemical methods (guaiac test).
- Ability to detect small amounts of blood not visible to the naked eye.
- Transferrin detection, a more stable blood protein, allows identification of bleeding even from upper gastrointestinal tract.
- Absence of false positives due to certain food substances.
- Indications for the test:
Diagnosis of hidden bleeding suspected in ulcerative and inflammatory gastrointestinal diseases, polyps, intestinal tumors, hemorrhoids, and other conditions potentially accompanied by internal bleeding without visible signs.
- Test specifics:
- Stool sample is collected in a clean container without urine or water contamination.
- For increased accuracy, collection of several samples spaced a few days apart is recommended.
- Patients are advised to avoid certain medications and foods that could affect results (recommendations depend on the specific lab protocol).
- Interpretation of results:
A positive result indicates hidden gastrointestinal bleeding requiring further examination to identify the cause. A negative result reduces the likelihood of bleeding but does not entirely exclude the need for monitoring based on clinical presentation.
- Conclusion:
Immunochemical fecal occult blood testing is an important and informative screening method for gastrointestinal diseases, capable of detecting even minimal bleeding and guiding timely further diagnostics and treatment.