A colonoscopy is a procedure that helps detect and prevent colon cancer. Experts recommend colon cancer screening for all adults starting at age 45, with repeat screenings at least every 10 years. People who have a higher risk of developing colon cancer should get a colonoscopy earlier and more often. This includes people with a family or personal history of colon cancer and those with certain forms of inflammatory bowel disease (IBD).
This article discusses how often a person should get a colonoscopy, what screening tests are available, and why earlier or more frequent screening may be recommended.
Who Should Get a Colonoscopy and How Often?
As you get older, your chances of developing colorectal cancer (cancer affecting the colon or the rectum) increase. Updated clinical guidelines recommend that most adults get screened starting at age 45, and then every 10 years after that as long as the results show no signs of cancer.
But for adults with certain risk factors for developing colon cancer, screening should begin sooner and happen more often. These factors include:
Family history of colon cancer: People with a first-degree relative (parent, sibling, or child) who has had colon cancer should start getting colonoscopies at age 40, or 10 years before the age that the immediate family member was diagnosed with colon cancer.
Personal history of colon cancer: Anyone who has had surgery to remove colon or rectal cancer should get a repeat colonoscopy within one year.
Previous colon polyp removal: If you've had an adenomatous polyp (or adenoma) removed during a colonoscopy, a follow-up screening is recommended in two to three years. The exact timing will depend on the type, size, and number of polyps removed.
Ulcerative colitis or Crohn's disease: These inflammatory bowel diseases are linked to a higher risk for developing colon cancer, and this risk increases the longer a person has IBD. Colonoscopies should start eight years after the IBD diagnosis, with follow-up screenings every one to two years after that.
Diverticulitis: People with this condition, which causes inflammation in the digestive tract, are advised to get a colonoscopy every five to eight years, and a few months after any related surgeries.
Age is the number one risk factor for developing colon cancer, which is why experts have broken down general colon cancer screening guidelines by age bracket.
Ages 45–75: Most adults should continue regular colonoscopies every 10 years during this time period.
Ages 76–85: Within this age group, the decision to receive colon cancer screenings should be made on a case-by-case basis between a healthcare provider and the patient. It may depend on a person's overall health, life expectancy, circumstances, and previous screening history. Your healthcare provider may also keep in mind evidence from a recent study showing that getting colonoscopies after age 75 can significantly reduce the risk of death from colon cancer.
Ages 85 and older: Experts advise against getting colonoscopies after the age of 85, as the risk of complications from the procedure may outweigh the benefits of the screening.
People with an average risk of developing colon cancer should start getting colonoscopies at age 45, with repeated screening at least every 10 years.
People with an increased risk of developing colon cancer should start getting colonoscopies at an earlier age and more frequently, as directed by your healthcare provider.
If you're unsure what this means for you, a healthcare professional will be able to help determine how often you should be screened.
What Happens During a Colonoscopy?
Getting a colonoscopy isn't pleasant, but it's an important and often lifesaving screening procedure that can help prevent colon cancer from developing. Here's what you can expect to happen leading up to and during the screening.
What to Expect
Once your colonoscopy is scheduled, your healthcare provider will give you bowel preparation instructions. These instructions include:
Drinking only clear liquids the day before the procedure
Stopping certain medications ahead of the procedure
Taking a liquid laxative at least 24 hours in advance to clear feces out of your colon
You can expect to have many bowel movements once the laxative starts working, which is why it's recommended to be near a bathroom on the day leading up to the procedure.
On the day of the exam, you’ll head to an outpatient facility, surgical center, or a hospital for the actual colonoscopy. You’ll change into a hospital gown, and a nurse will take your vitals before placing an intravenous (IV) line into a vein in your arm or hand. Sedative and pain medications will be given through your IV, so you’ll be very relaxed or mostly asleep during the procedure, which typically takes about 30–45 minutes to complete.
After you're sedated, a gastroenterologist (a doctor who specializes in the digestive system) will insert a long, flexible tube with a camera into the rectum. This tool, called a colonoscope, allows the gastroenterologist to take a look inside your colon for abnormalities like polyps (tissue growths), sores (ulcers), inflammation, and bleeding. If they spot anything abnormal, a tiny instrument may be inserted through the colonoscope to remove polyps or take a biopsy sample.
When the procedure is over, the colonoscope will be removed. A nurse will take you to a recovery area to be briefly monitored as the sedative wears off.
Post Colonoscopy Because of the sedative, you won't be able to drive for the next 24 hours, so you'll need a responsible adult available to help you home. Expect to feel a little drowsy, and, if possible, plan to clear your schedule of important tasks or duties for the rest of the day to recover.
Colonoscopy Side Effects and Risks
Just like other medical procedures, there is a chance that you could experience some side effects or risks after having a colonoscopy. These include more common side effects like:
Cramping, bloating, or gas for a few hours after the procedure
Light bleeding in the stool, particularly after a polyp has been removed
Nausea or vomiting as a reaction to the pain or sedative medications used
They can also include serious (though rare) risks, such as:
Perforation of the colon (an accidental hole in the lining of the colon from the tools used during the colonoscopy)
Infection inside the body or at the colonoscope insertion site
Significant bleeding
Research estimates that the rate of serious complications is roughly 1 or 2 for every 10,000 colonoscopies performed.
When to Call Your Doctor
Even though serious complications from a colonoscopy are rare, they can be potentially life-threatening. Call your healthcare provider right away or seek immediate medical attention if you experience any of these symptoms:
Severe pain
Fever or chills
Dizziness or feeling faint
Bleeding from the rectum that doesn't stop
Frequent bloody bowel movements
Trouble breathing, leg swelling, or chest pain
Other Screenings for Colorectal Cancer
A colonoscopy is just one type of screening test available for finding polyps or detecting colon cancer. There are other options that may work better for you depending on your individual situation.
Stool Tests
As the name suggests, stool tests use a sample from your stool (feces) to check for the presence of blood or cancer cells, which could indicate potential colon cancer. Stool tests are considered a reliable alternative to a traditional colonoscopy for people at average risk of developing colon cancer.
Types of stool tests include the fecal immunochemical test (FIT), guaiac-based fecal occult blood test (gFOBT), and the FIT-DNA test. Both gFOBT and FIT are available as home self-test kits, and should be completed every year.
Flexible Sigmoidoscopy
A flexible sigmoidoscopy is a miniature version of a traditional colonoscopy. It involves inserting a short, thin, flexible tube into the rectum, but it only gives views of the lower portion of the colon. A traditional colonoscopy views the entire colon.
On the plus side, bowel preparation tends to be less complicated, and sedation is often not required. But it may not be quite as sensitive in detecting colon cancer, so the Centers for Disease Control and Prevention (CDC) recommends people get a flexible sigmoidoscopy every five years.
Virtual Colonoscopy
A virtual colonoscopy (VC), also called a CT colonography, is a type of noninvasive imaging scan. It uses a series of X-rays to create a 3D image of the inside of the colon, rather than inserting a scope into the colon like a traditional colonoscopy.
Virtual colonoscopies take about 15 minutes and do not require an extensive bowel prep or sedation. It may be considered for people who decline or cannot have a traditional colonoscopy, but it isn't always covered by health insurance. If used, virtual colonoscopy should be performed every five years.
Screening Options Recap
There's no single "right" colon cancer screening test. Each option has advantages and disadvantages, depending on your overall health, circumstances, access to care, preference, and insurance coverage. Many insurance plans and Medicare help pay for colorectal cancer screening for people within the recommended age bracket or risk factor group. Talk to a healthcare provider about which screening test may be best for you.
Summary
A colonoscopy is a procedure used to detect and prevent colorectal cancer (cancer that affects the colon or rectum). Experts recommend that most adults should get a colonoscopy or other colon cancer screening test every 10 years, starting at age 45. Earlier and more frequent screening may help people with a family history of the disease and certain inflammatory bowel diseases that increase the risk of developing colon cancer.
A Word From Verywell
Preparing to get a colonoscopy may feel daunting, confusing, or scary. But remember that early detection of colon cancer is key for successfully treating the disease. Consider speaking with a healthcare provider about when your screening should begin based on your level of colon cancer risk. They can help answer any questions if you're feeling uneasy or unsure.
FREQUENTLY ASKED QUESTIONS
Why do I need a colonoscopy every three years? Some people who have had certain types of polyps (called adenomas) removed during a colonoscopy may need to get another colonoscopy after three years.21 This is because adenomas are more likely to turn into cancer. The exact timing for a repeat screening will depend on the type, size, and number of adenomas removed.
How does ulcerative colitis turn into cancer? After having ulcerative colitis for roughly a decade, the risk of colon cancer starts to increase. Experts think inflammation may play a role in changes in cells of the large intestine, which may turn cancerous. In people with ulcerative colitis, a yearly colonoscopy or other colon cancer screening may be recommended. Learn More: The Risks of Untreated Ulcerative Colitis
How fast can colon cancer develop after colonoscopy? It depends. In most cases, colon cancer grows slowly over the course of roughly a decade. Other research has shown that some patients receive a colon cancer diagnosis within three to five years of having a "normal" colonoscopy. It seems this may be more likely to happen in people over the age of 65, people with a family history of colon cancer, and people who have had a previous polyp removal.
How long will I be on the toilet for colonoscopy prep? Bowel preparation is the process of removing feces from the colon prior to a colonoscopy so the gastroenterologist can get a clear view of the colon. You’ll be instructed to start drinking a liquid bowel prep medication in doses the day before your procedure. The exact time frame will vary by person, but in general, frequent bowel movements start within two or three hours after taking the prep medication. You should plan to be close to a bathroom for the entire 24 hours before your procedure. Learn More: How to Do a Bowel Prep for Colonoscopy or Surgery