Can a history of diverticulitis cause a false positive result with Cologuard (Colon Cancer Screening Test)?

From the Guidelines

Yes, a history of diverticulitis can potentially cause a false positive result on a Cologuard test. Cologuard works by detecting altered DNA and blood in stool, which can be present in both colorectal cancer and inflammatory conditions like diverticulitis. When diverticulitis occurs, it causes inflammation in the colon that may lead to bleeding and cellular changes that the test can detect, even if no cancer is present. This is why patients with active diverticulitis or who have had a recent flare-up (within the last 3 months) are generally advised to delay Cologuard screening, as suggested by the American College of Physicians guideline 1.

According to the guideline, colonoscopy should be delayed by 6–8 weeks or until complete resolution of the acute symptoms, whichever is longer, to minimize the risk of perforation and technical difficulties 1. If you have a history of diverticulitis and receive a positive Cologuard result, your healthcare provider will likely recommend a follow-up colonoscopy to determine whether the positive result is due to cancer, polyps, or simply inflammation from diverticulitis.

Some key points to consider:

• The risk of colon cancer is higher in patients with complicated diverticulitis (7.9%) compared with patients with uncomplicated diverticulitis (1.3%) 1.
• Colonoscopy is advised after an episode of complicated diverticulitis and after a first episode of uncomplicated diverticulitis, but may be deferred if a recent (within 1 year) high-quality colonoscopy was performed and there were no findings warranting short interval follow up 1.
• Patients with recurrent uncomplicated diverticulitis should follow routine colorectal cancer screening and surveillance intervals unless alarm symptoms are present, such as change in stool caliber, iron deficiency anemia, blood in stool, weight loss, and abdominal pain 1.

It's essential to inform your doctor about your complete medical history, including diverticulitis, before undergoing any colorectal cancer screening test to ensure proper interpretation of results. The American College of Physicians guideline provides recommendations for the management of diverticulitis, including the use of colonoscopy and other diagnostic tests 1.

From the Research

Factors Associated with False-Positive Results

• A history of diverticulitis is not explicitly mentioned as a factor associated with false-positive results in the provided studies 2, 3, 4, 5, 6.
• However, the studies suggest that factors such as male sex, age ≥65 years, BMI ≥30 kg/m2, current smoking, use of aspirin, and a new diagnosis of inflammatory bowel disease (IBD) or other non-neoplastic findings at screening colonoscopy are associated with increased odds of a false-positive fecal immunochemical test (FIT) result 2.
• Additionally, the use of proton pump inhibitors has been associated with an increased likelihood of a false-positive FIT result 3.

Performance of Stool-Based Tests

• Multitarget stool DNA testing has been shown to detect significantly more cancers than FIT, but with more false-positive results 5.
• The sensitivity and specificity of multitarget stool DNA testing for colorectal cancer and advanced adenoma have been reported to be high, with areas under the curves (AUCs) ranging from 0.841 to 0.982 6.

Clinical Value of Multi-Target Stool Fecal Immunochemical Test-DNA

• The clinical diagnostic value of multi-target stool fecal immunochemical test-DNA (FIT-DNA) test for colorectal cancer and advanced adenoma has been investigated, with reported sensitivities and specificities of 91.6% and 89.1%, respectively 6.
• However, the studies do not provide direct evidence on the impact of a history of diverticulitis on the accuracy of FIT-DNA test results.