Cologuard (Multitarget Stool DNA Test)

A home stool test that looks for altered DNA and hidden blood linked to colon cancer and advanced polyps. It is a screening test, not a diagnosis.

AI-verified against cited sources. Awaiting expert reviewAlso called mt-sDNA, sDNA-FITLOINC 77354-9

What it is

Cologuard is a stool test you collect at home and mail to a lab. The lab looks for altered DNA from the lining of the colon and for tiny amounts of blood you cannot see. Colon cancers and some advanced polyps can shed these signs into the stool. The result is reported as negative or positive. It is made for adults aged 45 and older at average risk of colon cancer. Cologuard Plus is a newer version of the same kind of test.

Why it matters

Colon cancer can cause no symptoms at first. Screening aims to find it, or polyps that could become cancer, early. Cologuard is one of several screening choices that guidelines accept. In large studies it found about 9 in 10 cancers, but only about 4 in 10 advanced polyps, so a negative result makes cancer less likely without ruling it out. About 1 in 10 people without advanced findings still get a positive result. A positive result is not a diagnosis. Its job is to tell you that a colonoscopy is the next step.

If it’s high

A positive result means the test found altered DNA or blood that is linked to colon cancer or advanced polyps. It is not a cancer diagnosis. In the studies, roughly 1 in 10 people without advanced findings still had a positive result. The next step is a colonoscopy, which lets a clinician look at the colon directly and remove polyps. Guidelines from the US Preventive Services Task Force and the American Cancer Society both say a positive stool test should be followed by a colonoscopy.

Common causes

A false-positive result, where no cancer or advanced polyp is found (about 1 in 10 people without advanced findings in the studies)
Advanced precancerous polyps (advanced adenomas or large serrated polyps of 1 cm or more)
Colorectal cancer

What can help

Contact the clinician who ordered the test soon to plan a colonoscopy, since the screening benefit depends on following up a positive result
Ask whether your insurance covers the follow-up colonoscopy, because coverage rules differ by plan
Tell your clinician about any bowel symptoms, past polyps, or colon cancer in your family

What can affect your result

Who it is for: adults 45 and older at average risk. Exact Sciences says not to use it with a history of adenomas, inflammatory bowel disease or a hereditary syndrome, a personal or first-degree family history of colorectal cancer, or a positive result from another screening method within that method's interval
Test version: Cologuard Plus was designed for fewer false positives than the original Cologuard
Diarrhea or blood in your urine or stool at collection
Shipping delay beyond the same or next day
Polyp type and size: the test finds cancers far more often than advanced polyps
Diarrhea: the lab needs a typical stool, so Exact Sciences asks you to wait until your bowel movements return to normal before collecting.
Exact Sciences says not to provide a sample if you have diarrhea or have blood in your urine or stool.
The kit must be shipped the same day you collect the sample, or the next day at the latest. Exact Sciences suggests avoiding weekends and holidays to prevent shipping delays.
Collection amount: the stool sample should be larger than the cap of the preservative bottle but not larger than the bottle itself.
No fasting, diet change or bowel prep is needed.

This is a one-time screening snapshot of the sample you collect, not a marker to track week to week.

When to talk to a clinician

If your result is positive, contact your clinician soon to plan a colonoscopy. Do not wait for your next screening date. If you see blood in your stool, have black or tarry stools, a lasting change in bowel habits, belly pain that does not go away, or unexplained weight loss, contact your clinician whatever your screening result was. A negative screening test does not rule out cancer, and symptoms call for a different kind of check than screening.

Questions you could ask

Is Cologuard a good screening choice for me, given my age, family history and bowel health?
When should I be screened again if my result is negative?
When can I schedule a colonoscopy, and who will arrange it?
Will my insurance cover the follow-up colonoscopy?

Questions people ask

Does a positive Cologuard mean I have cancer?

No. A positive result means the test found altered DNA or blood that is linked to colon cancer or advanced polyps, and it is a reason to have a colonoscopy. Many people with a positive result do not have cancer. The colonoscopy is how you find out what is going on, and polyps can be removed during it.

If my result is negative, am I done?

A negative result makes cancer less likely, but it does not rule it out, and the test misses many advanced polyps. The American Cancer Society and Exact Sciences advise repeating the screening in 3 years, and the US Preventive Services Task Force lists every 1 to 3 years. If you notice blood in your stool or a lasting change in bowel habits, contact your clinician instead of waiting for the next screening.

Do I need to prepare or change what I eat?

No. Exact Sciences says there is no fasting, diet change or bowel prep. Wait to collect your sample if you have diarrhea. Follow the kit steps, add the preservative, and ship the kit the same day or the next day at the latest.

Show the science and sources

For clinicians and researchers

The original Cologuard (multitarget stool DNA, mt-sDNA) combines quantitative molecular assays for KRAS mutations, aberrant NDRG4 and BMP3 methylation and beta-actin (a human DNA reference) with an immunochemical hemoglobin assay. A logistic-regression algorithm turns these into one score, and a score of 183 or more was positive in the pivotal trial (Imperiale 2014). In that trial of 9,989 average-risk evaluable participants, sensitivity was 92.3% for colorectal cancer (FIT 73.8%) and 42.4% for advanced precancerous lesions (FIT 23.8%), including 69.2% for polyps with high-grade dysplasia and 42.4% for sessile serrated polyps of 1 cm or more. Specificity was 86.6% among people with non-advanced or negative findings and 89.8% among people with a negative colonoscopy (FIT 94.9% and 96.4%). About 166 people needed to be screened with mt-sDNA to find one cancer. The next-generation test (Cologuard Plus) was evaluated in BLUE-C in 20,176 asymptomatic adults aged 40 or older having screening colonoscopy: sensitivity 93.9% (95% CI 87.1 to 97.7) for colorectal cancer and 43.4% for advanced precancerous lesions, specificity 90.6% for advanced neoplasia and 92.7% for non-neoplastic findings or a negative colonoscopy, compared with FIT at 67.3%, 23.3%, 94.8% and 95.7% (Imperiale 2024). Both versions found more cancers than FIT but had lower specificity. Exact Sciences states that Cologuard Plus found 95% of colon cancers in a study of nearly 19,000 average-risk people aged 45 and older, with a 9% false-positive rate in people without cancer or advanced polyps. Both tests are FDA-approved, prescription-only, qualitative tests for adults 45 and older at average risk. The American Cancer Society (2018) lists mt-sDNA every 3 years and says all positive results on non-colonoscopy screening tests should get timely colonoscopy. The USPSTF (2021) lists stool DNA-FIT every 1 to 3 years for ages 45 to 75 (grade A for 50 to 75 and grade B for 45 to 49) and states that positive stool-test results need follow-up colonoscopy. The interpretation narrative LOINC (77353-1) is reported separately from the presence result (77354-9).

LOINC 77354-9 (primary), 77353-1. Specimen: stool.

Sources

Multitarget stool DNA testing for colorectal-cancer screening, New England Journal of Medicine (2014)
Next-Generation Multitarget Stool DNA Test for Colorectal Cancer Screening, New England Journal of Medicine (2024)
Colorectal Cancer: Screening (recommendation statement and screening strategies), US Preventive Services Task Force (2021)
Colorectal cancer screening for average-risk adults: 2018 guideline update from the American Cancer Society, CA: A Cancer Journal for Clinicians (2018)
Important Risk Information for Cologuard (indications for use), Exact Sciences
Understanding Your Cologuard Plus Test Results, Exact Sciences
How to Use a Cologuard Plus Test, Exact Sciences
Returning Your Cologuard Plus Kit Through UPS, Exact Sciences

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.