A colonoscopy is a medical procedure performed to inspect the inside of the rectum and colon (large intestine). During a colonoscopy, a healthcare provider inserts a flexible tube with a camera attached to the end into your anus and up your large intestine.

Healthcare providers use colonoscopies to diagnose ulcers, polyps, and colon or rectal cancer (colorectal cancer). Colonoscopies can also show areas of irritation and swelling in the rectum and colon, which is helpful for monitoring certain digestive disorders. 

Most adults need a colonoscopy every 10 years once they turn 45. Some people have a higher risk of colorectal cancer and require earlier or more frequent screenings. People with certain diseases may also need colonoscopies earlier and more frequently. 

Colonoscopies are an important part of preventive healthcare. Colorectal cancer is the third leading cause of cancer death among adults in the United States. Several factors affect how often you need a colonoscopy to screen for colorectal cancer, including:

• Age: Colorectal cancer is most often diagnosed in people aged 65-74. About 10.5% of new cases occur in people younger than 50, though that rate has steadily increased over time. Because of these statistics, it’s recommended that people aged 45-75 at average risk for colorectal cancer get screened every 10 years. Frequency usually declines once you’re over 75.
• Medical history: You may require more frequent colonoscopies if you have a history of colorectal cancer, ovarian cancer, inflammatory bowel disease, or Lynch syndrome. 
• Family history: If you have a family member who has been diagnosed with colorectal cancer, your healthcare provider may recommend a different screening schedule. 
• Previous colonoscopy results: If you have a history of colon polyps (tumors that develop in your large intestine that are usually non-cancerous but sometimes develop into cancer) or abnormal colonoscopy results, your healthcare team may recommend more frequent colonoscopies. 

Colonoscopies aren’t only used to screen for colorectal cancer. They can also be used to diagnose and monitor other health conditions, such as digestive disorders. The frequency at which you have colonoscopies in these cases can depend on factors like new or worsening symptoms.

The U.S. Preventive Services Task Force (USPSTF) recommends that adults of average risk for colon cancer begin regular colonoscopies at age 45. You’re considered to be at average risk if you don’t have a personal or family history of colorectal cancer, if they’ve never found certain polyps in previous screenings, if you don’t have inflammatory bowel disease (IBD), and if you’ve never received radiation to the belly or pelvis.

Between the ages of 45-75, it’s recommended that people at average risk for colon cancer get a colonoscopy every 10 years.  

Adults aged 75-85 should discuss the risks and benefits of colonoscopies with their healthcare providers. At this age, factors like overall health and prior screening history should dictate colonoscopy frequency.

It is recommended that people older than 85 don’t get screened for colon cancer. The potential risks of colonoscopies do not outweigh the possible benefits at that older age. 

In people who are at high risk for colorectal cancer, a colonoscopy may be considered surveillance. People who have a higher risk of colorectal cancer may need to start regular colonoscopies before age 45. They may also require the procedure more frequently than every 10 years. 

Your healthcare provider may recommend starting colonoscopies to check for colorectal cancer before age 45 if you have any of the following risk factors for colorectal cancer:

• History of colorectal cancer or polyps that could have become cancerous
• Family history of colorectal cancer
• History of IBD, such as ulcerative colitis or Crohn’s disease
• Family history of adenomatous polyposis (FAP) or Lynch syndrome 
• History of radiation to the abdominal or pelvic area

The American Cancer Society recommends the following colorectal surveillance frequency based on your medical history:

• History of colorectal cancer: A colonoscopy is usually performed one year after surgery to remove the cancerous part of the colon.
• History of polyps: Most people have a repeat colonoscopy three years after a polyp was found, but frequency depends on the type, size, and number of polyps.
• IBD: A colonoscopy to check for cancer would typically be done eight years after an IBD diagnosis (you might need more frequent colonoscopies to monitor the IBD itself). After the initial surveillance colonoscopy, regular cancer surveillance is usually done every 1-3 years.
• Certain genetic syndromes: A colonoscopy is performed in the teen years and repeated as needed. 
• History of radiation therapy: Typically, you’d get a colonoscopy 10 years after radiation or at age 35—whichever comes first. You’d then continue regular screenings every 3-5 years.

Colonoscopies can also help monitor certain chronic health conditions—for example, to monitor disease progression and determine if treatment is working. 

Your healthcare team may recommend regular colonoscopies to monitor the following health conditions: 

• Inflammatory bowel disease: Ulcerative colitis (UC) and Crohn’s disease are chronic conditions that cause inflammation in the colon. Your healthcare provider may recommend a colonoscopy to diagnose the condition, monitor the inflammation, and check to see if treatment is working. 
• Infectious diseases: If you develop symptoms of a serious digestive tract infection, your healthcare team may recommend a colonoscopy to determine the cause. Possible symptoms of an infection include fever, diarrhea, abdominal pain, and blood in the stool. 
• Functional bowel disorders: If you develop gastrointestinal symptoms like pain, diarrhea, constipation, and bloating with no known cause, your healthcare provider may recommend a colonoscopy to determine the cause. 

Like any medical procedure, colonoscopies come with risks. The potential benefits for most healthy adults, such as detecting cancer, outweigh the risks. However, once a person reaches 85 years old, the risks are not worth the benefits of continuing screening. 

Possible risks of a colonoscopy include:

• Bleeding: Bleeding after colonoscopy occurs in 15 out of every 10,000 procedures. 
• Perforation: The scope can tear the intestinal wall when the provider directs the tubed camera through your intestines. A perforation occurs in three out of every 10,000 procedures. 
• Medication reaction: It is rare but possible to experience breathing or heart problems from anesthesia used during a colonoscopy. 

Talk with your healthcare provider about how to prepare for your colonoscopy. Provide them with a current list of your medications, vitamins, and supplements. Your provider will likely ask you to stop taking any blood thinning medications, such as aspirin or Advil (ibuprofen), a few days before your procedure. Your provider will also recommend a special diet and bowel prep regimen.

Special Diet 

It is important to eat a special diet in the days before a colonoscopy. The colon has to be emptied of all stool (poop) so that your healthcare provider can have a clear view of the walls of your large intestine. 

Your provider will give you a detailed list of what you can and cannot eat and when those restrictions start. Typically, you should avoid foods that are rich in fiber, such as whole grains, raw vegetables, beans, nuts, and seeds, starting several days before your colonoscopy.

You will also be told to follow a clear liquid diet for a specific amount of time leading up to your appointment. Clear liquids in this diet include:

• Water 
• Fruit juice with no pulp 
• Sport drinks in light colors (lemon, lime, orange)
• Plain coffee or tea 
• Fat-free broth or bouillon 
• Gelatin in light colors 

Bowel Prep

Colonoscopy bowel prep refers to the regimen you follow to clean out your colon before a colonoscopy. You may be asked to take laxatives in the form of liquids, pills, or powders, in addition to a large amount of liquid. 

Bowel prep will cause diarrhea, and you should eventually experience stools that are clear liquid. It is important to stay near a bathroom while following a bowel prep regimen. Even though it may feel difficult, it is important to complete the entire bowel prep. 

Having a colonoscopy may produce feelings of uncertainty or anxiety. It often helps to know what to expect.

A colonoscopy takes less than an hour to perform. You will wear a hospital gown and lie on your side on an exam table. The healthcare team will place an intravenous (IV) line and administer sedatives or anesthesia so that you will not be awake or feel anything during the procedure.

After the procedure, you will likely need to stay at the hospital or outpatient center for about 60 minutes as the sedatives wear off. It is common to feel bloated and cramping during this time. If your provider removed polyps or tissue for a biopsy, you may experience light bleeding from the anus.

You won’t be able to drive yourself home, so plan to have a friend or family member drive you home and help you inside.

A colonoscopy is a medical procedure that inspects the inside of the large intestine (the rectum and colon). It can help diagnose colon or rectal cancer (colorectal cancer) and detect ulcers, polyps, and inflammation.

Most adults at average risk of colorectal cancer should start colonoscopy screenings at age 45 and have one every 10 years. Once you are 76, you can likely have less frequent colonoscopies.

People at an increased risk for colorectal cancer may require more frequent colonoscopies. You may also need more frequent colonoscopies or start them at a younger age if you have a digestive disease that needs monitoring.