What is the recommended order for an occult stool test?

Ordering Fecal Occult Blood Testing for Colorectal Cancer Screening

For average-risk asymptomatic adults aged 45-75 years, order annual fecal immunochemical testing (FIT) or high-sensitivity guaiac-based fecal occult blood testing (gFOBT), with collection of 2 samples from each of 3 consecutive bowel movements at home, and ensure colonoscopy follow-up for any positive result. 1, 2

Test Selection and Protocol

Preferred Testing Options

• FIT is preferred over traditional gFOBT due to superior sensitivity for advanced colorectal neoplasia (26.3% vs 7.4%), improved specificity, and no dietary restrictions required 3, 4
• High-sensitivity gFOBT (e.g., Hemoccult SENSA) is acceptable if FIT is unavailable, but requires dietary restrictions 1, 5
• Both tests must be performed annually to achieve mortality reduction of 15-33% demonstrated in randomized controlled trials 1, 2

Collection Protocol

• Collect 2 samples from each of 3 consecutive bowel movements at home 1
• For gFOBT: instruct patients to avoid aspirin, NSAIDs, vitamin C, red meat, poultry, fish, and certain raw vegetables for 3 days before and during collection 1
• For FIT: no dietary restrictions needed 1, 2
• Do NOT rehydrate guaiac slides, as this increases false-positive rates unpredictably 1

Age-Based Screening Recommendations

Starting Age

• Begin screening at age 45 years for average-risk adults (qualified recommendation) 1
• Age 50 years remains a strong recommendation if earlier screening is not feasible 1, 2

Stopping Age

• Continue screening through age 75 years for adults in good health with life expectancy >10 years 1, 5
• For ages 76-85 years: base decisions on prior screening history, comorbidities, and life expectancy 1, 5
• Discontinue screening after age 85 years 1

Critical Follow-Up Requirements

Positive Test Management

• Any positive result on any specimen requires complete colonoscopy to examine the entire colon 1, 2
• Do not repeat stool testing if positive—proceed directly to colonoscopy 1
• Colonoscopy was the diagnostic procedure used in efficacy trials and is substantially more accurate than other follow-up options 1

Patient Counseling Requirements

• Patients must commit to annual testing for effectiveness 1
• Patients must agree to colonoscopy if positive, or the screening program should not be recommended 1
• Explain that stool tests are less likely to prevent cancer compared to colonoscopy, as they primarily detect cancer rather than adenomatous polyps 1

Common Pitfalls to Avoid

Inappropriate Testing Scenarios

• Never use single-sample gFOBT from digital rectal exam in the office—this has very low sensitivity and is not recommended for screening 1
• Do not order FIT or gFOBT in patients with visible blood in stool—these patients require direct colonoscopy without preliminary stool testing 6
• Do not delay colonoscopy to perform stool testing in symptomatic patients, as this may postpone diagnosis of significant pathology 6

Processing Errors

• Ensure gFOBT slides are not rehydrated, as this dramatically increases false-positive rates while making test readability unpredictable 1
• Process FIT in a clinical laboratory; gFOBT can be processed in office or laboratory 1
• Collect all 3 samples, as test sensitivity improves with each additional specimen 1

Alternative Screening Options

If patients decline stool testing or prefer structural examination:

• Colonoscopy every 10 years 1, 2
• CT colonography every 5 years 1, 2
• Flexible sigmoidoscopy every 5 years 1, 2
• Multi-target stool DNA test every 3 years 1, 2