What is Colonoscopy?

Colonoscopy is an examination of the large intestine, or colon, using a long flexible instrument called a colonoscope. This test may be done for a variety of reasons. Commonly it is done to investigate the finding of blood in the stool, diarrhea, abdominal pain, a change in bowel habits, or an abnormality noted on a colon x-ray or barium enema. Colonoscopy is also recommended in patients over age 50 to screen for colon cancer and colon polyps.

What Happens During the Procedure?

An intravenous (IV) will be started in your arm. You will be connected to instruments to continuously monitor your pulse, blood pressure, electrocardiogram, and oxygen level. A short acting anesthetic is then given so you will sleep through the procedure. A certified registered nurse anesthetist (CRNA) will care for you during the procedure to ensure your safety.
The examination is performed while you are lying on your left side. The doctor will examine your rectum first with a finger and then the colonoscope will be gently inserted. The colonoscope will be carefully passed through the colon and then slowly withdrawn.
If abnormalities are found, biopsies may be taken for examination by a pathologist. Small growths (polyps) may also be found in the colon and can usually be removed safely. Small bleeding sites are often cauterized or injected to stop bleeding.

This examination usually takes 15 to 30 minutes depending on how long it takes to pass the scope around the colon and treat any abnormalities that are found.

After the Procedure

The anesthetic wears off very quickly. Most patients are awake 5-10 minutes after the procedure is done. You will be observed for about 30 minutes before going home. You will not be allowed to drive for the rest of the day. You may be drowsy for several hours afterward.
Following the colonoscopy, the doctor will talk with you and your family and give them a complete report of the test findings. A follow-up visit may be scheduled, at the discretion of the physician.


Colonoscopy is a very safe procedure. Complications occur in less than 1% of patients.

  • Reaction to the medications given for sedation are uncommon, but include allergic reactions, difficulty breathing, or irritation of the vein used to give the medication.
  • Bleeding is a possibility, and can occur several days or even as long as two weeks after the procedure, usually after a polyp has been removed.
  • Perforation or puncture of the colon may occur. A perforation is a serious problem and in most cases would require surgery in order to repair the perforation in the colon. Fortunately, this is quite rare.
  • If you experience severe pain, bleeding, or any problems after the procedure, please contact our office immediately.

Like every other test available, colonoscopy is not perfect and there is a small risk that polyps or even a colon cancer can be missed with this examination. If you have persistent rectal bleeding or other symptoms, then other testing or even repeat colonoscopy might be needed. Please discuss these symptoms with your physician.


Colonoscopy is the best test available to detect and treat abnormalities inside the colon. However, like any medical test, it is not 100% accurate.

Barium enema is an X-ray test that can detect many abnormalities in the colon. However, it misses abnormal findings in the colon more often than colonoscopy, and if an abnormality is found, colonoscopy often must be done to biopsy or remove the abnormality.

Flexible sigmoidoscopy is a limited examination of the lower part of the colon. This procedure is done in the office, usually without sedation. It is recommended as a general screening examination to detect colon polyps or tumors in patients who have no symptoms of disease. We no longer recommend or offer flexible sigmoidoscopy as we consider it to be inadequate as a screening procedure.

Virtual Colonoscopy is a new test in which the patient undergoes a high speed CT scan. The computer reassembles the images to create a view of the colon that looks like what is seen at colonoscopy. Preparation still requires a laxative preparation, and the colon is filled with air to create the images. The bowel prep and air can be uncomfortable. If abnormalities are found, conventional colonoscopy may still be required. Virtual colonoscopy may not be covered by your insurance plan. The procedure is still being refined, but still has been shown to miss up to 25% of larger polyps and about half of smaller polyps that are detected by standard colonoscopy. Its role in colorectal cancer screening and diagnosis has not been clearly defined.

Video Capsule Endoscopy is a specialized test for examination of the small intestine. It is not an alternative to colonoscopy.


Complete preparation of the colon is very important, so that a thorough examination of your colon can be performed. Your doctor will chose a laxative preparation for you. Please carefully follow the instructions.
Iron preparations should not be taken for at least 4 days before colonoscopy. On the day of your test, important medications (such as those for high blood pressure or heart disease) should be taken with a small amount of clear liquid early in the morning, at least 3 hours before colonoscopy.
If your procedure is scheduled in the morning, you are not to eat, drink, or chew anything after midnight until your procedure is completed. If your procedure is scheduled after noon, you may have a cup of clear liquids of your choice in the early morning and then nothing to eat, drink or chew until after your procedure is completed. You may take your regular prescription medications in the early morning.
If you are diabetic or taking Coumadin, please ask for specific instructions regarding your medication. Please let you doctor know if there is any chance you might be pregnant at the time of your procedure.