A colonoscopy is a procedure that diagnoses and helps monitor inflammatory bowel disease (IBD). This can play an essential role in preventing and treating colorectal cancer.

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IBD is a range of conditions that cause chronic inflammation of the gastrointestinal (GI) tract. Two of the most common IBD conditions are ulcerative colitis (UC) and Crohn’s disease.

Doctors diagnose IBD using multiple methods. One diagnostic measure is a colonoscopy. This allows a doctor to visually inspect different parts of the GI tract by inserting a small camera into the anus using a lighted, flexible tube.

This article discusses the uses and benefits of a colonoscopy, its preparation, and what to expect during and after. It also considers possible side effects, answers common questions, and shares the personal experience of Fanny Tristan, who has Crohn’s disease.

IBD colonoscopy diagnoses symptoms that could indicate IBD. Colonoscopy allows accurate diagnosis of UC or Crohn’s disease in up to 9 out of 10 cases.

Doctors will use colonoscopies to find the cause of symptoms such as:

Medical professionals will also use a colonoscopy to look for other indicators of IBD, including:

  • irritated and swollen tissue
  • ulcers
  • polyps
  • cancer growths

Colon polyps are small growths that doctors may find on the lining of the colon and rectum. They are common in adults, and most are harmless.


Regular follow-up colonoscopies also help monitor the condition. Doctors use them for surveillance to detect any possible complications.

As people with IBD are at increased risk of developing colorectal cancer, doctors will look for early cancer signs during a colonoscopy. They also help prevent colorectal cancer by locating and removing the precancerous polyps that cause cancer.

Although most people with IBD will not experience colorectal cancer, early detection is critical. Colorectal cancer is very treatable when detected early using regular colonoscopies.

Fanny’s story: Monitoring procedures

“Every 6 months to 1 year, I have colonoscopies. However, the procedure is subject to my deductible, so I cannot afford to get the procedure as often as my doctor recommends.”

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Read more about colonoscopy and Medicare.

Doctors instruct people on how to prepare for a colonoscopy beforehand. They will discuss the following:

  • what and what not to eat before the procedure
  • medications or supplements a person takes
  • any health conditions a person has

A person will drink a liquid solution or take pills, called a bowel preparation before the colonoscopy.

Examples of these preparations include:

  • MiraLAX
  • MoviPrep
  • Suprep

They usually take the preparation in 2 doses: 1 dose the evening before and the other on the same day, 4–6 hours before the procedure.

The preparation may cause diarrhea and discomfort. However, it is important for someone to finish the preparation, as it removes debris and excess stool from the intestines. The doctor will then have a clear view of a person’s intestinal lining.

Learn more about colonoscopy preparation.

Diet and timelines

A few days before a colonoscopy, people must follow a low fiber diet to ensure they digest food correctly.

A person may need to stop eating solid foods 1–3 days before a colonoscopy and start following a clear, liquid diet up until a few hours before the procedure.

Learn about foods to eat before a colonoscopy.

Fanny’s story: How to prepare before

“Three days before the procedure, I have to take MiraLAX twice daily, after lunch and dinner. Then, before the procedure, I need to fast the entire day and only have clear liquids or soup broth, tea, or coffee. At one point in the day, I need to take more MiraLAX with a light Gatorade. Also, I need to take 5mg [milligram] of dulcalax every 15 minutes for an hour. I then spend the rest of the day bracing myself to use the bathroom through the evening and night. It’s quite interruptive to my day, and you don’t get a good night’s sleep before the procedure.

When you arrive for your appointment, they check your blood pressure and have you take a pregnancy test.

I’m encouraged to avoid drinking alcohol and any lactose-related products before and after the procedure.”

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People undergo colonoscopies at hospitals or other healthcare facilities. Each colonoscopy procedure is between 30–60 minutes. Overall the hospital stay will be 2–3 hours, including preparation and recovery time.

People typically receive sedation before their colonoscopies. This is to minimize discomfort and prevent pain during the procedure. The medical staff will monitor vital signs throughout, including:

  • heart rate
  • blood pressure
  • oxygen levels

Some people may opt out of sedation, or a doctor may perform the procedure without it.

During a colonoscopy, doctors place a person on a surgical table and carefully insert a colonoscope into the person’s anus. From there, they move the camera into the person’s rectum and colon.

As the specialist moves the colonoscope, the end-mounted camera will send a TV image to a monitor. The
doctor uses this to visually examine a person’s large intestine. The medical professional may occasionally move the person to adjust the view from the scope.

They will also use the scope to inflate the person’s large intestine with air. This provides a better view of the intestinal lining.

Fanny’s story: During the procedure

“The colonoscopy does not hurt. You are asleep and don’t recall any part of the examination. You are laid to rest for an hour after the procedure, which is quite short. The procedure is about 15 minutes long.”

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If a person has had sedation, they should avoid driving for 24 hours after the colonoscopy, so someone will need to collect them. This is to allow time for the sedatives to wear off. They should also avoid returning to work or making important decisions.

They may feel bloated or have excess gas for a few hours afterward. People typically recover and return to their usual diets by the following day.

Light bleeding from the anus is typical after the procedure if the doctor has removed polyps or abnormal tissue.

Fanny’s story: Postprocedure and results

“You must have someone pick you up from your procedure. You feel lightheaded from the anesthesia right after. I was given a bag of pretzels for the road. You have a lot of gas throughout the day after the procedure.

I have a follow-up with my doctor, who thoroughly reviews the results and shows me images from the procedure. It’s very thorough.”

Editor’s note: It is important that a person does not take a taxi cab home on their own following a colonoscopy. Another adult must supervise a person during the journey and provide postprocedure care at home.

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The risks of colonoscopy-related side effects are low, but complications can occur. Risk factors can include older age and later detection of IBD.

Two of the most common complications are bleeding and perforation of the colon. These are very rare and usually occur if a person has a polyp removed. Delayed bleeding can occur up to 2 weeks after a colonoscopy. Doctors will determine this with a repeat colonoscopy and treat any perforation with surgery.

Other less common risks include abdominal pain or reactions to the sedative used during the procedure.

Below are some common questions about colonoscopies.

Does it hurt?

Colonoscopies do not usually hurt. Doctors will sedate or anesthetize a person for the entire procedure, so the person will not feel pain.

If a person asks for only light sedation, they may feel some discomfort or pain.

Doctors can also administer a general anesthetic, meaning individuals will be unconscious and not recall the procedure.

What does it feel like?

A person may feel certain sensations during a colonoscopy, but they should not be painful. They could feel:

  • the camera entering the body, but this does not usually hurt
  • stomach cramps as the tube pass through the bowels
  • slightly bloated as their bowels have air pumped into them

If a doctor takes samples or removes any growths, the person will not feel any sensation or pain.

Are there any emotional or physical effects?

Many people undergoing a colonoscopy can experience anxiety before the procedure, especially on the day. However, individuals undergoing repeat surveillance colonoscopies find their anxiety levels reduced with subsequent procedures. There may also be some physical side effects, but the rate of adverse effects is low.

What should a person eat before a colonoscopy?

Doctors will give a person written instructions on what to eat before the procedure. This includes following a diet low in fiber and low in foods such as:

This is to reduce the amount of residue in a person’s stool.

People may also need to follow a clear liquid diet in the days before the procedure, avoiding:

  • red-colored drinks
  • purple-colored drinks
  • gelatin

A colonoscopy allows doctors to diagnose and monitor IBD. They are essential in helping prevent and treat colorectal cancer.

People must follow the specific preparation before the procedure to ensure doctors can obtain a clear image of the intestines to detect any inflammation.