What is the follow-up for a positive fecal occult blood test (FOBT) result with one out of three tests indicating blood in the stool?

From the Guidelines

A positive fecal occult blood test (FOBT) with one out of three samples showing blood requires a colonoscopy as the recommended follow-up procedure. This is necessary regardless of whether one, two, or all three samples are positive, as any blood detection warrants further investigation 1. The colonoscopy should be scheduled within 2-4 weeks of the positive FOBT result, though the exact timing may depend on the patient's risk factors and symptoms.

Key Considerations

• The presence of blood in stool, even in just one sample, can indicate various gastrointestinal conditions that require proper diagnosis and treatment 1.
• A positive FOBT is associated with an approximately 1:10 chance of cancer or a 37% chance of a polyp 1.
• Annual FOBT should not be performed in combination with colonoscopy in an average-risk patient, but any positive result on FOBT should be followed up with colonoscopy 1.

Procedure Details

• During the colonoscopy, the gastroenterologist will examine the entire colon to identify the source of bleeding, which could range from benign conditions like hemorrhoids or polyps to more serious issues like colorectal cancer.
• Prior to the procedure, patients will need to complete a bowel preparation regimen, typically involving clear liquids for 24 hours and a prescribed laxative solution.
• It's essential not to delay this follow-up, as early detection of colorectal cancer significantly improves treatment outcomes 1.

Recommendations

• The most recent guidelines recommend using high-sensitivity guaiac tests for FOBT, with a sensitivity of greater than 70% and a specificity of more than 90% for detecting cancer 1.
• Annual FOBT screening is recommended when used alone, and any positive result should be followed up with colonoscopy 1.

From the Research

Follow-up for a Positive Fecal Occult Blood Test (FOBT) Result

If one out of three fecal occult blood tests is positive for blood, the following steps may be considered:

• A positive FOBT result indicates the presence of blood in the stool, which can be a sign of colorectal cancer or other gastrointestinal disorders 2.
• The sensitivity and specificity of FOBT vary depending on the type of test used, with immunochemical tests generally having higher sensitivity and specificity than guaiac tests 2, 3.
• If a FOBT result is positive, a colonoscopy is typically recommended to further investigate the cause of the bleeding 4, 3.
• During a colonoscopy, a doctor can visualize the entire colon and remove any polyps or other lesions that may be causing the bleeding 4.
• If no lesions are found in the colon, an upper GI endoscopy may be considered to investigate the upper gastrointestinal tract for potential sources of bleeding 5, 6.
• The decision to perform an upper GI endoscopy should be individualized and based on clinical judgment, taking into account the patient's symptoms, medical history, and other factors 5.

Key Considerations

• The prevalence of upper GI lesions in patients with a positive FOBT result is significant, with approximately 30% of patients having clinically significant lesions 6.
• Anemia is a significant predictor of upper GI cancers and other clinically significant lesions in patients with a positive FOBT result 6.
• The cost-efficacy of dual endoscopy (colonoscopy and upper GI endoscopy) as a standard of care for all patients with a positive FOBT result is unclear and requires further study 6.

Potential Next Steps

• Patients with a positive FOBT result should undergo a colonoscopy to investigate the cause of the bleeding 4, 3.
• If no lesions are found in the colon, an upper GI endoscopy may be considered to investigate the upper gastrointestinal tract for potential sources of bleeding 5, 6.
• Patients with anemia or other symptoms suggestive of upper GI bleeding may require more urgent evaluation and treatment 6.