Understanding the Differences Between Colonoscopies and Cologuard
March 10, 2025
While 90% of colorectal cancers are preventable, they remain the second most common cause of cancer deaths for men and women combined. It is expected to cause nearly 53,000 deaths in 2025, according to the American Cancer Society.
Vicki Sharma, DO, general surgeon at Trinity Health Muskegon and Muskegon Surgical Associates, provides insights on standard screening methods.
Vicki Sharma, DO
General Surgeon
Trinity Health Muskegon Hospital
A referral from a primary care provider is required to schedule a colonoscopy. Don't have a primary care provider? Start your search here.
View DetailsWhat are the differences between a colonoscopy and a Cologuard test?
Vicki Sharma, DO: A colonoscopy is a scope with a camera that looks at a colon’s walls. It directly assesses abnormalities, including polyps, cancers, mucosa (lining) changes, bowel disease, and more.
Cologuard is a stool sample that tests for DNA and blood from altered cells that indicate early signs of colon cancer.
How effective is a colonoscopy compared to Cologuard in detecting colorectal cancer?
Vicki Sharma, DO: Colonoscopies are highly effective at detecting both colorectal cancer and precancerous polyps (adenomas), with a sensitivity detection rate of more than 95%
Cologuard detects about 92% of colorectal cancers already present. Still, it only detects polyps (adenomas — benign tumors that can potentially turn into cancer) nearly 42% of the time.
What are the advantages and disadvantages of each screening method?
Vicki Sharma, DO: With a colonoscopy, we can detect polyps that are small enough to be removed easily and have not become cancerous yet. Before the procedure, it’s necessary to prepare by cleaning out the colon to ensure accurate results. Preparation typically includes reducing fiber intake, consuming only clear liquids and no solid food the day before, and ingesting a laxative solution prescribed by your doctor. You will receive specific details and a prep kit beforehand; following directions carefully is important.
A Cologuard test is less invasive but less sensitive to polyps and potential cancer.
In what situations would you recommend a colonoscopy versus Cologuard?
Vicki Sharma, DO: I always recommend a colonoscopy unless your doctor says it’s not recommended due to anatomical reasons or if you are too high risk to undergo the procedure.
Cologuard isn’t as effective at screening for colon polyps, and by the time the test turns positive, the polyps are more significant and more challenging to remove, or they have turned into cancer.
What are the potential risks associated with the two screening methods?
Vicki Sharma, DO: There are risks with colonoscopies, including bleeding and perforation — however, the risk is less than 1%.
The risks of Cologuard tests are false positive and negative results.
How often should individuals get screened for colorectal cancer?
Vicki Sharma, DO: Screening colonoscopies start at age 45 unless you are a high-risk individual with a family history of colon cancer, bowel disease, or familial disorders. If your colonoscopy is normal, repeat every 10 years. If polyps are found, the time interval shortens depending on number and size.
Cologuard is recommended at 45, and if normal, recommended every three years. It is not recommended for high-risk individuals or diagnostic purposes.
Learn more about colorectal cancer screenings and talk to your doctor about getting screened.
A referral from a primary care provider is required to schedule a colonoscopy. Don't have a primary care provider? Start your search here.