The short answer
Colonoscopy or Cologuard: which is better?
For most people who can have one: colonoscopy. It is the only screening test that looks at the whole colon and can remove a precancerous polyp in the same visit, before it has the chance to become cancer.
Cologuard is a real screening test, and far better than none. But in its main study it found about 43 of 100 advanced precancers, it cannot remove one, and a positive result means a colonoscopy anyway.
Answered by Stephen Rudolph, MD, a practicing gastroenterologist. Self-funded, with no money from any test maker. Reviewed November 2026.
Cologuard Plus · BLUE-C study · New England Journal of Medicine, 2024
The difference, in one picture.
Take 100 people who already have advanced precancer: a larger polyp, or one with cell changes that put it closer to cancer. One round of Cologuard Plus found this many.
- 43
- detected by the stool test
- 57
- not detected by the stool test
Finding cancer matters. Finding precancer and removing it is how colon cancer is prevented. A colonoscopy looks at the colon directly, and a polyp that is found can usually be taken out during the same exam.
That is one number. Here is the full case.
Colonoscopy and Cologuard, side by side.
| What matters | Colonoscopy | Cologuard Plus (stool DNA) |
|---|---|---|
| Finds cancer that is already there | Yes, by looking directly | About 94 of 100 |
| Finds advanced precancer | Yes, by looking directly. It can still miss some. | About 43 of 100 |
| Removes polyps | Yes, usually during the same exam | No |
| If something is found | Removed or sampled during the exam | You need a colonoscopy to finish |
| What a normal result means | No polyps were seen. Small ones can be missed. | Cancer is very unlikely. About 1 in 15 still had advanced precancer. |
| How often, if normal | Usually every 10 years | Every 3 years |
| What it asks of you | A prep, sedation and a ride home | A kit at home. No prep. |
Detection figures come from one screening round in the BLUE-C study (2024), which checked the stool test against colonoscopy. “1 in 15” is from the FDA review of Cologuard Plus. Testing intervals follow current screening guidelines.
Colonoscopy “remains the gold standard for colorectal cancer screening.”
From the Society’s announcement of its updated screening guideline. The guideline lists several tests; this is how it describes colonoscopy. Read the announcement
From the doctor
Which test would a gastroenterologist choose?
“If you can have a colonoscopy, have the colonoscopy. It is the one screening test that can look at your whole colon, find a polyp and take it out in the same visit. If you can’t, or you won’t, a stool test done on schedule is far better than no test. I only ask that you choose knowing what each one can and cannot do.”
Stephen Rudolph, MD
Gastroenterologist, Minnesota. I earn income from clinical care, including colonoscopy. You should know that. Funding & disclosures
The questions people ask next.
Tap a question for the short answer. Each one links to the fuller story, with its sources.
Is Cologuard as good as a colonoscopy?
At finding cancer that is already there, it comes close: about 94 of 100 in its main study. At finding advanced precancer, it does not: about 43 of 100. And it cannot remove anything.
Cologuard checks a stool sample for signals. A colonoscopy looks at the colon itself.
Does “95% cancer detection” mean it finds most precancer, too?
Which test do the guidelines recommend?
Several, which is where the confusion starts. The U.S. Preventive Services Task Force and the American Cancer Society list colonoscopy and stool tests, including stool DNA tests such as Cologuard, as options for people at average risk, without formally ranking them. Recommended is not the same as equal.
In announcing its 2026 guideline, the American Cancer Society said colonoscopy “remains the gold standard for colorectal cancer screening.”
My Cologuard was negative. Am I in the clear?
For cancer, very likely. For precancer, not necessarily. In the FDA’s review of Cologuard Plus, about 1 in 15 people with a negative result still had advanced precancer.
A negative result means test again in three years. It does not mean nothing is there.
What if my Cologuard is positive?
Then you need a colonoscopy to finish. A positive result is a signal, not a diagnosis, and your screening isn’t complete until that colonoscopy is done. The American Cancer Society advises having it promptly, preferably within six months. Insurance generally treats it as part of screening.
So the colonoscopy you hoped to skip becomes the next step. Starting with colonoscopy makes it one step, not two.
When is Cologuard a reasonable choice?
When a colonoscopy isn’t right for your health, isn’t available soon, or you have decided against it. A stool test done on schedule, with a colonoscopy after any positive result, is far better than no screening.
Stool tests are for people at average risk who have no symptoms. If you have bleeding or other symptoms, a close relative with colon cancer, or past polyps, talk with your clinician first. Your plan may differ.
Is a colonoscopy worth the prep?
The prep is the part people dread: an evening and a morning near a bathroom. It is also what lets your doctor see, and remove, small polyps. Most people are sedated and comfortable for the exam itself.
After a normal, high-quality colonoscopy, most people at average risk can wait 10 years for the next one. Cologuard repeats every three years. Serious complications are uncommon: about 3 in 10,000 screening colonoscopies cause a tear in the colon, and about 15 in 10,000 cause major bleeding.
What about FIT, or the new blood test?
FIT is a yearly stool test for hidden blood. In the same study, one round found about 67 of 100 cancers and 23 of 100 advanced precancers, so it depends on being repeated every year.
The blood test, Shield, found about 83 of 100 cancers but only 13 of 100 advanced precancers in its main study. The American Cancer Society recommends it only for people who decline or don’t complete the other tests. Neither can remove a polyp, and a positive result on either means a colonoscopy.
That is the short answer. Here is the whole picture.
The homepage walks through it in four steps. It takes about five minutes, and it is worth it before you choose a test.
Sources for this page
- BLUE-C study of Cologuard Plus. New England Journal of Medicine, 2024. One screening round, checked against colonoscopy. Funded by Exact Sciences, the maker of Cologuard. Open the source
- U.S. Food and Drug Administration. Cologuard Plus: summary of safety and effectiveness data (P230043). Open the source
- U.S. Preventive Services Task Force. Colorectal cancer: screening. 2021. Open the source
- Lin et al. Evidence review for the U.S. Preventive Services Task Force (complication rates). JAMA, 2021. Open the source
- American Cancer Society. Announcement of the updated colorectal cancer screening guideline. May 27, 2026. Open the source
- Chung et al. A cell-free DNA blood-based test for colorectal cancer screening (the Shield test). New England Journal of Medicine, 2024. Funded by Guardant Health, the maker of Shield. Open the source
- Fendrick et al. Patient and physician screening preferences, updated predictions. 2025. Sponsored by Exact Sciences. Open the source
Reviewed November 2026 by Stephen Rudolph, MD. General education, not medical advice. Colonoscopy First is this campaign’s position, not a universal guideline. Your clinician knows your history; this page doesn’t.