Colonoscopy is an outpatient exam that is performed with the patient lightly sedated. The procedure provides significant information used to which specific treatment will be given. In certain cases, therapy can be administered through the endoscope. Serious complications rarely occur from colonoscopy. Colonoscopy is the visual examination of the large intestine (colon) using a lighted flexible fiberoptic or video endoscopy. The colon begins in the right-lower abdomen and looks like a big question mark as it moves up and around the abdomen, ending in the rectum. It is 5-6 feet long. The colon has a number of functions including withdrawing water from the liquid stool that enters it so that a formed stool is produced.


The flexible colonoscopy is a remarkable piece of equipment that can be directed and moved around the many bends in the colon. These colonoscopes now come in two types. The original purely fiberoptic instrument has a flexible bundle of glass fibers that collects the lighted image at one end and transfers the image to the eye piece. The newer video endoscopes use a tiny, optically sensitive computer chip at the end. Electronic signals are then transmitted to the scope to a computer which displays the image on a large video screen. An open channel in these scopes allows other instruments to be passed through in order to perform biopsies, remove polyps or inject solutions.


There are many types of problems that can occur in the colon. The medical history, physical exam, laboratory tests and x-rays can provide information useful in making a diagnosis. Directly viewing the inside of the colon by colonoscopy is usually the best exam. Colonoscopy is used for:

  • Colon cancer-a serious but highly curable maglignancy
  • Polyps – fleshy tumors which usually are the forerunners of colon cancer
  • Colitis (ulcerative or Crohn’s)-chronic recurrent inflammation of the colon.
  • Diverticulosis and Diverticulitis-pockets along the intestinal wall that develop over time and can become infected.
  • Bleeding lesions – bleeding may occur from different points in the colon.
  • Abdominal symptoms, such as pain or discomfort, particularly if associated with weight loss or anemia.
  • Abnormal barium x-ray exam
  • Chronic diarrhea, constipation, or a change in bowel habits
  • Anemia


To obtain the full benefits of the exam, the colon must be clear and free of stool. The patient receives instructions on how to do this. It involves drinking a solution which flushes the colon clear or taking laxatives and enemas. Usually the patient drinks only clear liquid and the physician will advise the patient regarding the use of regular medcations during that time.

Learn more about Colonoscopy Preparation


Colonoscopy is usually performed on an outpatient basis. The patient is mildly sedated, the endoscope is inserted through the anus and moved gently around the bends of the colon.. If a polyp is encountered a thin wire snare is used to lasso it. Electrocauery (electrical heat) is applied to painlessly remove it. Other tests can be perfomred during colonoscopy including biopsy to obtain a small tissue specimen for microscopic analysis. The procedure takes 15-30 minutes and is seldom remembered by the patient.


After the exam, the physician explains the findings to the patient and family. If the effects of the sedatives are prolonged, the physician may suggest an appolintment at a later date. If a biopsy has been performed or a polyp has been removed, the results of these are not available for 3 to 7 days.


A colonoscopy is performed to identify and/or correct a problem in the colon. The test enables a diagnosis to be made and specific treatment can be given. If a polyp is found during the exam, it can be removed at that time, eliminating the need for a major operation later. If a bleeding site is identified, treatment can be administered to stop the bleeding. Other treatments can be given through the endoscope when necessary.


Bloating and distension typically occur for about an hour after the exam until the air is expelled. Serious risks with colonoscopy, however, are very uncommon. One such risk is excessive bleeding especially with the removal of a large polyp. In rare instances, a tear in the lining of the colon can occur. These complications may require hospitalization and rarely, surgery. Quite uncommonly a diagnostic error or oversight may occur.

Due to the mild sedation, the patient should not drive or operate machinery following the exam. For this reason, someone needs to be available to drive the patient home.