Pros and Cons of At-Home Cologuard Tests

Colon cancer, sometimes called colorectal cancer, is the third most common cause of cancer death among people of any sex. Fortunately, it can be detected and prevented with early screening methods, which you can start at age 45.

The preferred method for screening for colon cancer is a colonoscopy, a type of imaging test that detects colon abnormalities. It's performed using a flexible tube with a camera (colonoscope) that's inserted through the anus and rectum.

What to Know About Cologuard Tests - Illustration by Michela Buttignol

Verywell / Michela Buttignol

Another colon cancer screening method, called Cologuard, has gained in popularity because it is less invasive and more convenient than a colonoscopy. It was approved in August 2014 by the Food and Drug Administration (FDA). With the COVID-19 pandemic, Cologuard's use has become widespread because it can be done at home.

While there are some benefits to the Cologuard screening, there are also drawbacks. A major concern is its lack of accuracy. It is also not a replacement for a colonoscopy.

This article, will discuss the purpose of a Cologuard test, who is a good candidate, how it is different from a colonoscopy, and more.  

Purpose of a Cologuard Test 

The Cologuard test uses a stool sample to look for microscopic blood and altered DNA. It starts with at-home test collection using special containers for the stool sample. After you have the stool sample ready, you send it to a lab for testing.

Cologuard looks for changes in your DNA that could indicate precancerous polyps (growths in the colon lining) or colon cancer. It combines two tests: fecal immunochemical testing (FIT) to look for microscopic amounts of blood and DNA screening for abnormal cancer cells.

Colon cancer can be detectable using Cologuard because the lining of the colon sheds cells several times a day. These cells end up in the stool. Abnormal cells from a cancerous tumor or precancerous polyps are also shed into the stool, along with blood from any broken blood vessels.

What Are Polyps?

Polyps are growths on the colon’s surface that could grow into cancer.  

When to Think About Taking a Cologuard Test  

Your healthcare provider might recommend a Cologuard screening every three years after age 45. The test is recommended for people who have an average risk for cancer.  

Average risk means you do not have:

  • A personal history of colon polyps or colon cancer
  • Family history of colon cancer
  • Inflammatory bowel disease (Crohn’s disease and ulcerative colitis)

What Is Inflammatory Bowel Disease?

Inflammatory bowel disease is a condition that includes two chronic diseases of the gastrointestinal tract: Crohn's disease and ulcerative colitis. These conditions cause long-term inflammation and symptoms such as diarrhea, abdominal pain, and rectal bleeding.

Who Should Get a Colonoscopy Instead 

For some people, a colonoscopy is a better option than Cologuard. People with a personal or family history of colon cancer or colon polyps or who have inflammatory bowel disease should get a colonoscopy instead of using a Cologuard test.

A colonoscopy is also recommended when someone has signs and symptoms of colon cancer. Signs that indicate colon cancer include constipation or diarrhea, blood in the stool, changes to shape or color of stool, rectal bleeding, and/or abdominal pain or cramping.  

Cologuard vs. Colonoscopy

The main difference between Cologuard and a colonoscopy is that Cologuard is noninvasive. Cologuard involves collecting a stool sample in the privacy of your home and shipping it to a lab. The colon is not imaged, and polyps are not removed. Also, there is no sedation or anesthesia needed for this test.

Abnormal Results

If the results of Cologuard are abnormal, your doctor will send you for a follow-up colonoscopy.  

A colonoscopy is an outpatient procedure in which you are sedated (given medication that will make you feel sleepy and less aware). Once you are under sedation, your doctor will use a thin scope to visualize the colon and remove any polyps. The removal of polyps has been proven to reduce the risk of colon cancer.

Another difference between the two tests is preparation. Cologuard generally doesn’t require any diet or medication changes or other preparation before taking a stool sample. Colonoscopy requires a bowel prep (clearing the colon of all residue with diet and medication) so that the colon can be empty for imaging.

The third difference between these two tests is how they detect polyps. A colonoscopy detects all types of polyps. Cologuard rarely detects small, early polyps and is best for detecting polyps that are large and advanced. Additional differences between the two screening methods are test accuracy and cost.  

Cologuard Accuracy  

Cologuard testing has its drawbacks, mainly when it comes to its accuracy, especially in comparison to a colonoscopy.  

According to data presented at the 2022 American Society of Clinical Oncology Gastrointestinal Cancers Symposium (ASCO GI), Cologuard has an overall sensitivity (the ability to correctly identify a person as positive) of 95.2% for colon cancer. Additional analyses showed 83.3% sensitivity for high-grade dysplasia (more severe precancerous lesions) and 57.2% for all advanced precancerous lesions.

A 2018 review in the journal Chronic Diseases and Translational Medicine found that stool sample testing is not as accurate for detecting precancerous polyps and lesions as colonoscopy. Further, false positives (a positive result when there is no cancer) are more likely with a stool test, which is why doctors prefer to send patients for colonoscopies.

Insurance Coverage and Cologuard Cost

When used as a screening method, most health insurance plans and state-funded Medicaid insurance will cover the cost of Cologuard.

The Affordable Care Act (ACA) requires all private insurers and Medicare to cover the cost of screenings for colon cancer because they are recommended by the U.S. Preventive Services Task Force. The ACA also prevents insurers from charging any out-of-pocket costs for preventive screenings.  

If are eligible for a preventive colon cancer screening and you have insurance, it is likely you can get a Cologuard test without having to pay any co-pays or deductibles. If you don’t have insurance or your insurance doesn’t cover it, you might be eligible for a flexible payment plan or financial assistance program from the makers of Cologuard.  

Hidden Costs of a Positive Cologuard Result  

According to one Forbes report, the cost of Cologuard is $649. A colonoscopy costs around $2,200. While that seems like a cost savings, Cologuard is done more frequently, either yearly or every three years, while colonoscopy is done only every 10 years in people who don't have polyps.  

Additionally, if a Cologuard test comes back positive, it is likely your doctor will request a colonoscopy to screen for cancer and remove any polyps. It is also possible that your insurance company will not code the follow-up colonoscopy as a screening exam.

That means the cost of the procedure may be applied toward your deductible and you might have to pay a co-pay.  

Where to Order  

You will need a prescription from your healthcare provider for Cologuard. If you and your provider decide that Cologuard is the best option, a kit will be ordered and shipped to your home. You should reach out to your healthcare provider if you have any questions once the Cologuard kit arrives.  

Cologuard Instructions  

The instructions for Cologuard are quite simple, and it only takes a few steps to complete the screening.  

You should complete the test within five days of receiving the kit.

The instructions provided by Exact Sciences, the manufacturer of Cologuard, are as follows:  

  • Start by removing only the items you need for your sample.
  • The stool sample should not be larger than the bottle of liquid included in the box.
  • Try not to get urine on the sample. You can keep this from happening by emptying your bladder first. You should also avoid getting toilet paper or other materials on the stool sample.
  • Collect a sample when you know you can return it within a day of collecting it.

To collect a sample: 

  • Place your large sample container into the toilet bracket according to the enclosed directions.
  • Sit on the toilet, have a bowel movement, and use the large sample container to collect the stool sample.
  • Once you have a sample, remove the container from the toilet bracket to a hard surface.
  • Scrape the sample and add it to a small sample container.
  • Fill the large sample container with the included preservative.
  • Seal and label both the small and large sample containers. Follow the enclosed directions for packing up the sample and sending it to the lab.

For specific details on collecting the sample, go to the Cologuard website for a video explanation and a step-by-step guide.

Once you have your sample ready to ship, drop it off at a UPS location. You can also call 844-870-8870 and Exact Sciences will schedule a UPS pickup.

Interpreting Your Results and Next Steps  

After the lab gets your stool sample, they will evaluate it and send the results directly to your healthcare provider. Test results will either be negative or positive.

A negative test means there were no significant levels of DNA or hemoglobin blood markers found in the stool associated with colon cancer or precancerous polyps in the colon.

A positive test means that Cologuard detected signs of precancerous polyps or colon cancer. If your test is positive, your doctor will want you to schedule a follow-up colonoscopy.

False negatives (tests that wrongly indicate you do not have a condition) and false positives are possible with Cologuard. A study reported in 2014 in the New England Journal of Medicine found 13% of Cologuard results were false positives and 8% were false negatives.

Cologuard must be repeated every three years if your test was negative. Once you have had a positive test, your doctor will recommend you have diagnostic colonoscopies for future screenings.

Colonoscopy Frequency

A colonoscopy can be repeated every 10 years if you have never had any polyps.  


Cologuard is a noninvasive screening tool for colon cancer and precancerous polyps. It looks for changes in the DNA and evidence of microscopic blood in stool. The test is collected in the privacy of your own home. Once you have a sample ready, you send it to the lab for testing.

Cologuard has gained popularity because it's less invasive and more convenient than going in for a diagnostic colonoscopy. It also comes with drawbacks, including concerns about accuracy and costs.  

A Word From Verywell

Both Cologuard and diagnostic colonoscopies come with pros and cons. When it comes to the best option for you, it is important to understand the benefits and drawbacks of each screening method.

Reach out to your healthcare provider about any concerns or questions you may have about Cologuard and colonoscopy screenings, as well as your risk for colon cancer or precancerous polyps.

Frequently Asked Questions

  • Is Cologuard worth the effort?

    For some people, Cologuard is the best option for them. But Cologuard comes with some limitations when compared to traditional colonoscopy screenings. Talk to your healthcare provider about whether Cologuard is the best option for you or whether you should opt for a colonoscopy.

  • How much stool does a Cologuard test require?

    The size of the sample needed for the Cologuard test is small. The sample you send to the lab should be at least the size of a grape.

  • What are other alternatives to colonoscopies?

    There are other testing methods that can test for colon cancer and precancerous polyps.

    These include fecal immunochemical testing (a small stool sample is tested for blood), fecal occult blood testing (a small stool sample is tested for blood), sigmoidoscopy (using a flexible scope to see the last third of the colon), and CT (computed tomography) colonography (advanced X-ray imaging of the colon).

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12 Sources
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