Management of Abnormal Fecal Immunochemical Test Results
Introduction to FIT Results
- The American Gastroenterological Association and other societies suggest that a fecal immunochemical test (FIT) result of 25 μg/g of hemoglobin exceeds the threshold for a positive test in most screening programs, indicating the need for further investigation with colonoscopy 2, 3
- The British Society of Gastroenterology reports that FIT has a high negative predictive value (0.99) at thresholds of 7-10 μg/g, meaning values above this range warrant investigation 3
Diagnostic Thresholds and Implications
- Most screening programs use positivity thresholds between 7-20 μg/g feces, with emerging evidence suggesting optimal cut-offs between 7-10 μg/g for symptomatic patients 3
- A patient's result of 25 μg/g is clearly above these established thresholds and cannot be dismissed as normal 2, 3
Importance of Complete Colonic Evaluation
- The British Society of Gastroenterology and other guideline societies emphasize that when a positive fecal occult blood test is found in a patient with hemorrhoids, complete colonic evaluation by colonoscopy is mandatory to rule out colorectal cancer and other significant bowel disease 1, 4
- Hemorrhoidal bleeding typically presents as bright red blood visible in the toilet bowl, not as occult (hidden) blood detected on FIT, highlighting the need for colonoscopy 1
- The estimated risk of colorectal cancer in patients with rectal bleeding ranges from 2.4-11%, making complete colonic evaluation essential 4
Patient Management and Communication
- The American College of Gastroenterology recommends telling the patient that the fecal immunochemical test is not normal and requires further investigation to rule out serious conditions including colorectal cancer 1, 2, 5
- Emphasize that this is a screening test designed to detect hidden blood that may indicate cancer or precancerous polyps, and that hemorrhoids cannot account for a positive FIT without excluding other causes 1, 2, 5