Colonoscopy: Information and What to Expect

Ian C. Langtree Content Writer/Editor for Disabled World
Published: 2014/03/15 - Updated: 2019/04/28
Contents: Summary - Introduction - Main - Related

Synopsis: Information on Colonoscopy, a medical procedure to see inside the colon and rectum to detect inflamed tissue, cancer ulcers, and abnormal growths in the bowel. During colonoscopy, a sedative, and possibly pain medication, helps keep patients relaxed. A sigmoidoscopy allows an examination of the distal portion (about 600 mm) of the colon.


A colonoscopy is an endoscopic examination of the large bowel and the distal part of the small bowel with a CCD camera or a fiber optic camera on a flexible tube passed through the anus. A colonoscopy can provide a visual diagnosis (e.g. ulceration, polyps) and grants the opportunity for biopsy or removal of suspected colorectal cancer lesions.

Main Digest

A colonoscope is a flexible tube that ranges in length from 4 feet to 6 feet. A small video camera is attached to the colonoscope so a doctor may take pictures of video of a person's large intestine.

At What Age Should You Have Your First Colonoscopy?

Routine colonoscopy to look for early signs of cancer should begin at age 50 for most people, earlier if there is a family history of colorectal cancer, a personal history of inflammatory bowel disease, or other risk factors. The doctor can advise patients about how often to get a colonoscopy.

Difference between colonoscopy and a sigmoidoscopy:

Medical societies recommend a screening colonoscopy every 10 years beginning at age 50 for adults without increased risk for colorectal cancer.

What is a Colonoscopy?

Continued below image.
Diagram with inset showing overview of colonoscopy procedure
Diagram with inset showing overview of colonoscopy procedure

Colonoscopy is a procedure used to see inside the colon and rectum. Colonoscopy can detect inflamed tissue, ulcers, and abnormal growths. The procedure is used to look for early signs of colorectal cancer and can help doctors diagnose unexplained changes in bowel habits, abdominal pain, bleeding from the anus, and weight loss. A colonoscopy may also be recommended by your doctor in order to check for:

What are the Colon and Rectum?

The colon and rectum are the two main parts of the large intestine. Although the colon is only one part of the large intestine, because most of the large intestine consists of colon, the two terms are often used interchangeably. The large intestine is also sometimes called the large bowel.

Digestive waste enters the colon from the small intestine as a semisolid. As waste moves toward the anus, the colon removes moisture and forms stool. The rectum is about 6 inches long and connects the colon to the anus. Stool leaves the body through the anus. Muscles and nerves in the rectum and anus control bowel movements.

How to Prepare for a Colonoscopy

Good bowel cleansing is essential for high-quality colonoscopy. The success of a colonoscopy is closely linked to good bowel preparation, with poor bowel prep often resulting in missed precancerous lesions, according to new consensus guidelines released by the U.S. Multi-Society Task force on Colorectal Cancer. Additionally, poor bowel cleansing can result in increased costs related to early repeat procedures. Up to 20 to 25 percent of all colonoscopies are reported to have an inadequate bowel preparation.

The doctor usually provides written instructions about how to prepare for colonoscopy. The process is called a bowel prep. Generally, all solids must be emptied from the gastrointestinal tract by following a clear liquid diet for 1 to 3 days before the procedure. Patients should not drink beverages containing red or purple dye. Acceptable liquids include

A laxative or an enema may be required the night before colonoscopy. A laxative is medicine that loosens stool and increases bowel movements. Laxatives are usually swallowed in pill form or as a powder dissolved in water. An enema is performed by flushing water, or sometimes a mild soap solution, into the anus using a special wash bottle. Patients should inform the doctor of all medical conditions and any medications, vitamins, or supplements taken regularly, including

People need to plan to remain at home during their preparation time because they will need to use the bathroom more often. Colon preparation causes loose and frequent stools and diarrhea so a person's colon will be empty for the test. If a person needs to drink a solution as part of their preparation, they need to be sure to have clear fruit juices or soft drinks to consume after the preparation because the solution may have an unpleasant or salty taste.

How is colonoscopy performed?

Examination of the Large Intestine:

During colonoscopy, patients lie on their left side on an examination table. In most cases, a light sedative, and possibly pain medication, helps keep patients relaxed. Deeper sedation may be required in some cases. The doctor and medical staff monitor vital signs and attempt to make patients as comfortable as possible.

The doctor inserts a long, flexible, lighted tube called a Colonoscopy, or scope, into the anus and slowly guides it through the rectum and into the colon. The scope inflates the large intestine with carbon dioxide gas to give the doctor a better view. A small camera mounted on the scope transmits a video image from inside the large intestine to a computer screen, allowing the doctor to carefully examine the intestinal lining. The doctor may ask the patient to move periodically so the scope can be adjusted for better viewing.

Once the scope has reached the opening to the small intestine, it is slowly withdrawn and the lining of the large intestine is carefully examined again. Bleeding and puncture of the large intestine are possible but uncommon complications of colonoscopy.

How a Colonoscopy Feels

Colon preparation will definitely cause diarrhea; some experience cramping as well. During the colonoscopy, a person might feel very sleepy and relaxed from the pain medication and sedative. The person may experience cramping or feel sharp pains as the colonoscope is moved or air is blown out of their colon. As the colonoscope is moved up the person's colon, they may feel the need to have a bowel movement and pass gas.

A suction machine is used to remove secretions and stool and might be loud, although it does not cause pain. The person will feel sleepy after being administered a sedative and pain medications. A number of people state they do not remember much about the colonoscopy because of the sedative.

Following the colonoscopy, a person may have cramping from gas pains and bloating. If a biopsy was done, or a polyp was removed, the person may have traces of blood in their stool for a few days. If polyps were removed, a doctor might instruct the person not to take NSAID's or aspirin for 7-14 days.

Removal of Polyps and Biopsy

A doctor can remove growths, called polyps, during colonoscopy and later test them in a laboratory for signs of cancer. Polyps are common in adults and are usually harmless. However, most colorectal cancer begins as a polyp, so removing polyps early is an effective way to prevent cancer.

The doctor can also take samples from abnormal-looking tissues during colonoscopy. The procedure, called a biopsy, allows the doctor to later look at the tissue with a microscope for signs of disease.

The doctor removes polyps and takes biopsy tissue using tiny tools passed through the scope. If bleeding occurs, the doctor can usually stop it with an electrical probe or special medications passed through the scope. Tissue removal and the treatments to stop bleeding are usually painless. Recovery

Colonoscopy usually takes 30 to 60 minutes. Cramping or bloating may occur during the first hour after the procedure. The sedative takes time to completely wear off. Patients may need to remain at the clinic for 1 to 2 hours after the procedure. Full recovery is expected by the next day. Discharge instructions should be carefully read and followed as there is a small chance for issues from a colonoscopy. The colonoscope or a small tool may tear the lining of a person's colon or cause bleeding. After a colonoscopy it is important to call the doctor promptly if you:

Results of a Colonoscopy

A colonoscopy is a test that allows some doctor to examine the inner lining of a person's large intestine and rectum. If a sample of tissue is collected during the procedure it will be sent to a lab for testing. Samples of colon tissue are usually sent to a pathology lab where they are examined under a microscope for diseases. Additional samples of colon tissue may be sent to a microbiology laboratory to find out if an infection is present.

A doctor might be able to tell a person their results promptly after the procedure, kind of like telling a drugged person to try to remember what someone else has said right after being drugged. Other test results are ready in 2-4 days. Test results for certain infections may be available in a number of weeks.

A, 'normal,' result of a colonoscopy finds a person's colon appearing pink and smooth with a lot of folds. There are no pouches, growths, inflammation or bleeding found. 'Abnormal,' colonoscopy results finds things such as hemorrhoids, cancer, polyps, one or more ulcers, pouches in the wall of the person's colon, or inflammation. A red and swollen lining of a person's colon may be caused by inflammatory bowel disease (IBD), or an infection.

What is a Virtual Colonoscopy?

A virtual colonoscopy (VC, or CT colonography or CT pneumocolon) is a medical imaging procedure using x-rays and computers to produce 2 and 3D images of the colon from the lowest part, the rectum, all the way to the lower end of the small intestine to examine the large intestine for cancer and growths called polyps.

During the exam, a small tube is inserted a short distance into the rectum to allow for inflation with gas while CT images of the colon and the rectum are taken.

During a virtual colonoscopy it is not possible to take tissue samples (biopsy) or remove polyps, so a conventional colonoscopy must be performed if abnormalities are found. In addition, VC does not show as much detail as a conventional colonoscopy, so polyps smaller than between 2 -10 millimeters in diameter may not show up on the images.

Continued below image.
Just one image of several thousand taken during a virtual colonoscopy MRI scan. The dark area is the actual colon.
Just one image of several thousand taken during a virtual colonoscopy MRI scan. The dark area is the actual colon.

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Cite This Page (APA): Langtree, I. C. (2014, March 15). Colonoscopy: Information and What to Expect. Disabled World. Retrieved May 19, 2024 from

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