Stool Test for Occult Blood (ELISA)

• Principle of the method:
  ELISA (enzyme-linked immunosorbent assay) uses specific antibodies that bind human hemoglobin or transferrin, allowing qualitative and quantitative detection of blood in stool. The method is based on antigen-antibody reaction with an enzyme label producing a measurable color signal.


• Advantages of immunochemical analysis:
  • High sensitivity and specificity compared to traditional chemical methods (guaiac test).
  • Ability to detect small amounts of blood invisible to the naked eye.
  • Detection of transferrin, a more stable blood protein, allows identifying bleeding even from upper gastrointestinal tract sections.
  • No false positives related 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 that may cause internal bleeding without visible signs.


• Test specifics:
  • Stool sample should be collected in a clean container without urine or water contamination.
  • For increased accuracy, collecting several samples over a few days is recommended.
  • Patients are advised to avoid certain foods and medications that may affect results (based on specific lab protocols).


• Result interpretation:
  A positive result indicates the presence of hidden gastrointestinal bleeding requiring further investigation to identify the cause. A negative result reduces the likelihood of bleeding but does not completely rule out the need for observation depending on clinical context.


• Conclusion:
  Immunochemical stool occult blood test is an important and informative screening method for gastrointestinal diseases, enabling detection of even minor bleeding and timely directing patients to further diagnosis and treatment.