Colonoscopy

Colonoscopy is the visual examination of the large intestine (colon) using a lighted, flexible fiberoptic or video endoscope. 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 to 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 colonoscope is directed and moved around the many bends in the colon. Electronic signals are transmitted up 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.

Preparation
To obtain the full benefits of the exam, the colon must be clean and free of stool. This involves drinking a solution which flushes the colon clean or taking laxatives and enemas. Usually the patient drinks only clear liquids and eats no food for the day before the exam.

The Procedure
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. Electrocautery (electrical heat) is applied to painlessly remove it. Other tests can be performed during colonoscopy, including biopsy to obtain a small tissue specimen for microscopic analysis. The procedure takes 15 to 30 minutes. A recovery area is available to monitor vital signs until the patient is fully awake. It is normal to experience mild cramping or abdominal pressure following the exam. This usually subsides in an hour or so.

Results
If a biopsy has been performed or a polyp removed, the results of these are not available for three to seven days.

Benefits
The test enables a diagnosis to be made and specific treatment can be given.

Alternative Testing
Alternative tests to colonoscopy include a barium enema or other types of x-ray exams that outline the colon and allow a diagnosis to be made. Study of the stools and blood can provide indirect information about a colon condition. These exams, however, do not allow direct viewing of the colon, removal of polyps, or the completion of biopsies.

Side Effects and Risks
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 hospitalisation and, rarely, surgery. Quite uncommonly a diagnostic error or oversight may occur.

Summary
Colonoscopy is an outpatient exam that is performed with the patient lightly sedated. The procedure provides significant information used to determine which specific treatment will be given.