Stool DNA test results may include:
Negative result. A test is considered negative if abnormal DNA changes common to colon cancer or precancerous polyps and signs of blood aren't found in the stool. Your doctor may recommend you repeat the test in three years.
Positive result. A test is considered positive if abnormal DNA changes common to colon cancer or precancerous polyps or signs of blood are found in the stool sample.
Your doctor may recommend additional testing — typically a colonoscopy to examine the inside of the colon to determine if cancer or polyps are present.
For every 20 people who undergo stool DNA testing, one or two will have a positive result, but no cancer or polyps will be found during a follow-up colonoscopy. In these instances, further testing is usually not recommended.
Nov. 16, 2017
- AskMayoExpert. Cologuard (stool DNA) test. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2017.
- Sweetser S, et al. Multi-target stool DNA test: Is the future here? Current Gastroenterology Reports. 2016;18:30.
- Bibbins-Domingo K, et al. Screening for colorectal cancer: US Preventive Services Task Force Recommendation Statement. JAMA. 2016;23:2564.
- Cologuard. U.S. Food and Drug Administration. https://www.accessdata.fda.gov/scripts/cdrh/devicesatfda/index.cfm?db=pma&id=320556. Accessed Aug. 30, 2017.
- Cotter TG, et al. Long-term follow-up of patients having false-positive multitarget stool DNA tests after negative screening colonoscopy: The LONG-HAUL cohort study. Cancer Epidemiology, Biomarkers and Prevention. 2017;26:614.
- Ahlquist DA (expert opinion). Mayo Clinic, Rochester, Minn. Aug. 31, 2017.