OCCULT BLOOD, FIT

This test requires one stool sample in iFOBT container provided in kit.  Raw stool samples will not be accepted.

• 15 days at room temp in collection device
• 30 days refrigerated

Qualitative screening for colorectal cancer.  Not intended to be used to evaluation occult GI bleeding in patient with anemia, iron deficiency, or suspected GI bleed; Guaiac occult blood test advised in those instances.

The Immunochemical Fecal Occult Blood (FIT) test differs from the Guaiac test.  Guaiac tests (like Hemoccult Sensa) develop a blue color in the presence of heme or other peroxidase-like or oxidizing compounds.  It is a nonspecific reaction that can be influenced by a number of foods and medications.  The fecal immunochemical test (often referred to as FIT) specifically detects the globin portion of human hemoglobin, and is not affected by diet or medications.  Additionally, the FIT test only requires one stool collection while the guaiac requires three.  However, globin is rapidly digested in the upper GI tract which compromises the use of FIT for global detection of occult bleeding.

When Guaiac test is preferred:

• Iron Deficiency, Anemia and suspected Upper GI Bleed:
  • The majority of pathologic occult GI bleeding arises from the upper GI tract, nearly twice as often as from the lower GI tract.
  • Guaiac stool tests are capable of detecting Upper GI Bleeds.

When FIT test is preferred:

• Colorectal Cancer Screening:
  • Studies have suggested that immunochemical tests, compared to stool guaiac tests, may have better performance characteristics for colorectal cancer screening, with increased sensitivity without loss of specificity. Patient willingness to be tested may also be higher with FIT compared to screening by stool guaiac, flexible sigmoidoscopy, or colonoscopy.

The American College of Gastroenterology supports the joint guideline recommendation that the older guaiac-based fecal occult blood testing be abandon as method for CRC screening.