What is Fecal Occult Blood Testing (FOBT)
• Screening for colorectal cancer in average risk population in the ambulatory setting
- Guaiac based (g-FOBT) or immunochemical test (FIT)
- g-FOBT is the older of the two and no longer recommended as first line screening
• Recommended screening use:
- Three separate stool samples. with applicator used to smear on card, NOT FROM DRE
• gFOBT often misused (particularly on inpatient setting) for indications other than CRC screening (100% of time)
Why FOBT is NOT appropriate for GIB/anemia evaluation
• False Positives
- Ingested blood: epistaxis, gingival bleeding. pharyngitis
- Mucosal inflammation: esophagitis, gastritis, IBD, cirrhosis
- Medications: NSAlDs. iron supplementation, ASA, coumadin, antiplatelets, anticoagulants
- Diet: red meat, broccoli, cauliflower, ETOH
• False Negatives:
- Ingestion of antioxidants (VitC)
- Denatured from upper GIB
• Does not change management and can lead to unnecessary testing, extended LOS
- University of Massachusetts GI Fellowship @UMassGI
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