Your Guide to Colonoscopy: How to Prepare and What to Expect

Medically Reviewed By Cynthia Taylor Chavoustie, MPAS, PA-C
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A colonoscopy is a procedure that examines the lining of your colon and rectum using a thin, flexible instrument called a colonoscope. Colonoscopy is an important screening tool for colorectal cancer. Preparation for colonoscopy involves fasting and drinking a laxative solution to cleanse the colon. This article will provide an overview of a colonoscopy, including reasons for colonoscopy. It will also discuss how to prepare for colonoscopy and what to expect during the procedure.

What is a colonoscopy?

Senior man drinking water
Miquel Llonch/Stocksy United

A colonoscopy is an important test that can detect colorectal cancer in its earliest, most curable stage. It also helps diagnose unexplained intestinal symptoms, such as changes in your bowel movements, abdominal pain, or rectal bleeding

Colonoscopy is only one method doctors use to test for colon cancer. Discuss all the screening and testing options with your doctor to understand which options are right for you.

What are reasons for a colonoscopy?

Doctors can use colonoscopy as both a diagnostic tool and a treatment procedure for certain conditions. A primary reason for colonoscopy is screening for colorectal cancer.

Screening for colorectal cancer

Routine colonoscopy is an effective screening tool for colorectal cancer. The U.S. Preventive Services Task Force (USPSTF) recommends screening for colorectal cancer in adults starting at age 45.

Previous guidelines recommended screening starting at age 50, and some insurance companies may only cover routine colonoscopy earlier for those with certain risk factors. Talk with your doctor and your insurance company about your eligibility for screening and the expected cost.

If you are younger than 45 years and have risk factors, your doctor may advise starting routine colonoscopy sooner. These risk factors include:

  • family history of colorectal cancer or certain kinds of polyps
  • personal history of colorectal cancer or certain kinds of polyps
  • prior radiation treatment to the abdomen or pelvis for treatment of previous cancer
  • personal history of inflammatory bowel disease, including Crohn’s disease or ulcerative colitis
  • family history of certain hereditary conditions affecting the colon

Other reasons for colonoscopy

Doctors may also use colonoscopy for reasons including:

  • Removing colon polyps: Polyps are small growths of cells that can form along the lining of the large intestine or rectum. They do not typically cause harm, but they can become cancerous.
  • Tissue biopsy: Doctors can also use a colonoscopy to collect a small tissue sample from the small intestine or rectum. Lab clinicians then test the tissue to diagnose conditions including colorectal cancer, ulcerative colitis, and Crohn’s disease.
  • Diagnosing the underlying cause of symptoms: A colonoscopy can help identify conditions that may be causing symptoms such as blood in stool, bowel movement changes, and unexplained weight loss.

How much does a colonoscopy cost?

The cost of a colonoscopy depends on several components, including your age, risk factors, and where you have the procedure.

The national average listed on healthcare sites ranges from around $2,300 to $2,750. Colonoscopy prices at high price hospitals can reach up to $27,670.

Costs associated with a colonoscopy include fees for:

  • the doctor who performs your colonoscopy
  • the location where you have your procedure
  • the anesthesiologist
  • the pathology lab that tests any tissue samples or polyps

It is important to note that you have a choice of where to receive your colonoscopy: in a hospital or in an independent outpatient clinic. In many cases, outpatient clinics may be a more affordable option.

Talk with your doctor about your options and the costs associated with each.

Does insurance cover colonoscopy?

Under the Affordable Care Act (ACA), private insurance companies and Medicare must cover the cost of colonoscopy screening, in accordance with USPSTF guidelines. If doctors remove polyps during the procedure, the cost of the full procedure also must still be covered.

The ACA also mandates that insurers cover a follow-up colonoscopy based on results from a noninvasive, stool-based screening test.

However, there may still be situations when you must pay for part of a colonoscopy procedure. Check with your insurance provider when planning your colonoscopy so you have an accurate understanding of estimated costs.

How do I prepare for my colonoscopy?

You are an important member of your own healthcare team. The steps you take before your colonoscopy can improve your comfort and help get the most accurate test results. 

Tell your doctor about your medications

When you schedule your colonoscopy, tell your doctor or care team about all medications you are taking. This includes over-the-counter medications, especially aspirin, as well as vitamins and supplements.

Your doctor may ask you to stop taking certain medications prior to the procedure. These include blood thinners and medications for diabetes.

Arrange for a ride home

Because you will receive sedation or anesthesia during your colonoscopy, you will not be able to drive yourself home. Plan for someone to take you home and stay with you for a few hours after the procedure.

Prepare your bowel

In order for your doctor to have accurate view of your large intestine, the colon must be completely clean for a colonoscopy.

To do this, your doctor will have you take steps to prepare your colon in the days before the procedure. These steps typically include:

  1. Getting a prescription for bowel preparation medications: This is a laxative treatment that may come in pill form, as a liquid, or as a powder. Your doctor may prescribe this up to a week prior to your procedure.
  2. Starting a clear liquid diet: Your doctor will advise you on which liquids are allowed. They will likely ask you to avoid items that are red or purple, as these can cause discoloration in the colon. Typical foods or drinks you can have include chicken broth, plain coffee with no cream or milk, and gelatin or sports drinks in lime, lemon, and orange flavors.
  3. Consuming the prep treatment: This process typically begins the morning before the day of your procedure. You will mix your prescribed powder or liquid with a specific amount of water. Chilling a liquid mixture ahead of time can help make drinking the solution easier.

The prep solution will stimulate your bowels and cause you to go to the bathroom several times. You will likely also need to consume a large amount of water or other clear fluid to help flush out your bowel.

Your doctor or care team will provide specific instructions and timing for these steps for your individual procedure.

Some people may find it unpleasant to drink all of the prep liquid, but it is important to complete the prep process as instructed. Contact your doctor’s office if you have difficulty during any step of your prep.

What happens during a colonoscopy?

Medical illustration of how a colonoscopy is performed in the lower intestine
Medical Illustration by Mekhi Baldwin

Your colonoscopy will be performed in a hospital or outpatient setting. The procedure takes about 30–60 minutes and generally includes these steps:

  1. You will dress in a patient gown.
  2. You will lie on your left side on a procedure table and pull your knees up to your chest.
  3. You will have a light sedative to make you drowsy and relaxed. Some doctors may use deeper sedation or anesthesia, which allows you to be asleep through the procedure.
  4. Your doctor will gently insert the colonoscope through the anus and into the rectum and colon. The image is transmitted onto a video screen.
  5. Your doctor will insert air into the colon. Stool and fluids are removed through the colonoscope as needed. This improves the view of the intestinal lining.
  6. Your doctor will slowly and gently pull the colonoscope back through the colon and rectum, examining the lining for any abnormalities. They will take photos of each area. If necessary, they may perform other procedures, such as polyp removal or tissue biopsy.

Will I feel pain?

Your comfort and relaxation are important to your care team. You may feel pressure and brief cramping during the procedure. If you receive deeper sedation or anesthesia, you may be asleep during the procedure.

Your doctor will give you enough pain and sedative medications so you stay comfortable. Tell your doctor if you are uncomfortable in any way.

What can I expect after my colonoscopy?

You might feel drowsy from the sedative and pain medications. You may have mild temporary abdominal cramping and pass the gas that doctors inserted during the procedure.

To reduce discomfort, take slow deep breaths to relax your abdominal muscles. Your doctor will treat your pain as needed. Tell your doctor if your pain does not respond to medication.

When can I go home?

Your doctor will discharge you when you are alert, breathing effectively, and your vital signs are stable. This generally takes less than an hour, depending on the type of sedation you have. 

You will not be able to drive and will need someone to drive you home and stay with you for at least a few hours.

When can I eat?

You should be able to start eating again once you leave the clinic or hospital. Although you will be hungry, you may want to start with light meals until your body adjusts and avoid alcoholic drinks for at least 24 hours. Your doctor will talk through any special dietary instructions before you leave.

When should I call my doctor?

It is important to keep your follow-up appointments after a colonoscopy. Contact your doctor for questions and concerns between appointments.

Call your doctor or seek immediate medical care if you have:

  • bleeding
  • fever (101°F or 38°C)
  • pain that does not go away with pain medication

Other frequently asked questions

These are some other questions people often ask about colonoscopy. The answers below have been reviewed by Cynthia Taylor Chavoustie, MPAS, PA-C.

How long does a colonoscopy take?

Preparing your bowel for colonoscopy can take up to 36 hours, depending on the timing of your procedure. The actual colonoscopy procedure takes about 30–60 minutes.

How long does it normally take to recover from a colonoscopy?

After your procedure, you may have about an hour of recovery time at the hospital or clinic before your doctor discharges you. Once you are home, you will be able to return to your normal activities within 24 hours.

Is a colonoscopy test painful?

After your colonoscopy, you may experience bloating or pain from air that doctors insert into the bowel during the procedure. Because you are under sedation, you likely will not feel pain or even be awake during your colonoscopy.

Do they put you to sleep for a colonoscopy?

You will receive sedation or anesthesia before your colonoscopy. This may make your feel drowsy or even put you to sleep so you are unaware of the procedure. During the colonoscopy, an anesthesiologist will monitor your vital signs and adjust sedation as needed.


Colonoscopy is a primary screening tool for colorectal cancer, allowing doctors to diagnose it in the early stages while it is still curable. Doctors also use colonoscopy to diagnose, evaluate, or treat conditions such as colon polyps, ulcerative colitis, and Crohn’s disease.

Preparing for colonoscopy involves following a liquid diet and taking a prescription laxative to cleanse the bowel. Colonoscopy occurs under sedation, so you will either be drowsy or asleep during the procedure.

Talk with your doctor about your risk factors and when you should start routine colonoscopy.

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Medical Reviewer: Cynthia Taylor Chavoustie, MPAS, PA-C
Last Review Date: 2022 Jun 30
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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