Overview and Definition

Colonoscopy is an outpatient procedure wherein the inside of your large bowel (colon and rectum) is examined and investigated. A colonoscopy procedure is generally performed to evaluate gastrointestinal problems such as abdominal pain and rectal bleeding. Typically performed by gastroenterologist, it is conducted using a device called a colonoscope.

The colonoscope is a long, thin, flexible tube, which is attached to a small video camera and connected to a TV monitor. Using the various controls that come with the device, the gastroenterologist guides the instrument to determine the possible causes of the gastrointestinal symptoms. There is a shorter version of the colonoscope called the sigmoidoscope, which is used for problems limited to the lower part of the large intestine.

Uses of Colonoscopy

A colonoscopy is one of the standard diagnostic procedures used to determine the causes of the following symptoms:

  • Blood loss
  • Bleeding from the large bowel
  • Chronic diarrhea
  • Changes in bowel habit
  • Abdominal or rectal pain

Colonoscopy is also a common procedure used to further investigate abnormalities identified through colonic X-rays or colonic CT scan. More importantly, it is used to accurately evaluate colon cancer and treat colon polyps, which are abnormal growths on the inner lining of the intestinal wall. Patients who have a previous history of colon polyps, ulcerative colitis, and colon cancer are usually advised to undergo periodic colonoscopy procedures.

Specialists also perform this non-surgical procedure to painlessly remove a suspicious-looking growth for biopsy and further analysis.

When to have a Colonoscopy

If you experience discomfort, pain or any of the aforementioned gastrointestinal symptoms, it is important that you see your general practitioner immediately. Depending on the nature and severity of the symptoms, your doctor may refer you to a gastrointestinal specialist, who can then perform investigative tests to evaluate the cause of your symptoms. Colonoscopy is usually recommended for moderate to severe gastrointestinal symptoms. How often one undergoes the procedure will depend on the severity of the abnormality or degree of risk found in the previous colonoscopies performed.

Meanwhile, for healthy patients, a colonoscopy is not really necessary unless you have risk factors, a previous history of colon polyps or a family history of colon cancer. Colon cancer screening is usually suggested starting from age 50 and every 10 years thereafter.

Before a Colonoscopy

To ensure accurate results, it is important that your bowel is emptied so the specialist will get a clearer view through the colonoscope. Your doctor will give you instructions for cleansing and bowel preparations that should be strictly followed or else the procedure will give unsatisfactory results and may have to be performed again. The instructions usually consist of:

  • Drinking large amounts of a special cleansing solution
  • Liquid diet for several days before the procedure
  • Intake of laxatives
  • Performing one or two enemas prior to the examination

A colonoscopy usually comes with a sedating medication. It is unsafe to drive within eight hours after the procedure, so make necessary arrangements.

It is also important that you consult your doctor about the medications that you are currently taking or if you have special medical conditions that may be a concern before, during or after the procedure is performed.

What to expect during a Colonoscopy

The entire procedure usually lasts at least 30 to 60 minutes. Your gastroenterologist will make sure that you are as comfortable as possible during the procedure. An intravenous line (IV) will be placed to make you feel relaxed and drowsy but still awake and cooperative. Once fully relaxed, your doctor will first perform a rectal exam, after which a fully lubricated colonoscope will be inserted into the rectum.

There is usually little or no discomfort at all when the scope is fully passed, although you may feel the need to move your bowels and a little cramping. The scope is very flexible that it can move around the curves of the colon. You may be requested to change position once in a while should it be necessary to help propel the scope further. If an abnormality is seen through the scope, a small amount of tissue may be removed for analysis ( biopsy), or in the case of benign polyps, may be fully removed. In the case of rectal bleeding, the site of bleeding is identified and samples of tissue are obtained for proper evaluation and treatment. Colonoscopy procedures often allow very accurate diagnosis and treatment without the need for surgical intervention.

After a Colonoscopy

After the procedure, you will be taken to a recovery area until the full effects of the sedating medication have worn off. Patients often feel some cramping or gas sensation that usually passes quickly. Certain medications, such as blood thinners, may have to be avoided if the tissue samples or polyps were removed.

Minor bleeding might occur at the site where polyps or tissue samples have been removed, but this usually goes away within a few days.

Unless otherwise instructed, you can return to your normal diet immediately after the colonoscopy. However, alcohol, driving, regular outdoor activities, and operation of heavy machinery must be avoided until after 24 hours following the colonoscopy.

Possible complications of Colonoscopy

Colonoscopy is a safe procedure, although minor complications can occur in rare instances such as puncturing or perforation of the colon walls. You must tell your doctor right away if you experience excessive and prolonged rectal bleeding, severe abdominal pain, fever and chills within 2 weeks after the procedure. These complications are rare but possible. Be sure to discuss with your doctor if you have certain concerns regarding the procedure. Follow-up check-ups may also be necessary depending on the results of the procedure.

Colonoscopy is currently the most accurate method for detecting, diagnosing and treating abnormalities within the colon. The test has minor inconveniences but is generally safe. It has been proven to detect colon diseases early and have saved many lives.


  • American Gastroenterological Association (2013). “Colonoscopy” Available: http://www.gastro.org/patient-center/procedures/colonoscopy
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