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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.
Equipment
The flexible colonoscope is a remarkable piece of equipment
that can be directed and moved around the many bends in the
colon. 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 up the scope to a computer which displays the image
on a large video screen. An open channel in both scopes allows
other instruments to be passed through in order to perform
biopsies, remove polyps or inject solutions.
Reasons For The Exam
There are many types of problems that can occur in the colon.
The medical history, physical exam, laboratory tests and x-rays
can provide useful information. 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
malignancy
• 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-hidden or massive bleeding that may
occur from different points in the colon
• Abdominal symptoms, such as pain or discomfort
• Abnormal barium x@ray exam
• Chronic diarrhea or constipation
Preparation
To obtain the full benefits of the exam, the colon must be
clean and free of stool. The patient receives instructions on how
to do this.
It involves drinking a solution which flushes the colon clean
or using laxatives and enemas. Usually the patient drinks only
clear liquids and eats no food for the day before the exam. The
physician advises the patient regarding the use of regular
medications during that time.
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 and is seldom remembered
by the sedated patient. A recovery area is available to monitor
blood pressure until the patient is fully awake. It is normal to
experience mild cramping or abdominal pressure. This usually
subsides in an hour or so.
Results
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 appointment at a later
date. If a biopsy has been performed or a polyp removed, the
results of these are not available for three to seven days.
Benefits
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.
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. These exams, however, do not allow direct
viewing of the colon or removal of polyps or biopsies to be done.
In addition, study of the stools and blood can provide indirect
information about a colon condition.
Side Effects and Risks
Bloating and distension typically occur for about an hour
after the exam until air is expelled. Serious risks with
colonoscopy, however, are uncommon. One such risk is excessive
bleeding, especially with the removal of a polyp. In rare
instances, a perforation or 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, a driver
should be available.
In Summary
Colonoscopy is an outpatient exam that is performed with the
patient lightly sedated. The procedure provides significant
information upon which specific treatment can be given. In
certain cases, therapy can be administered directly through the
endoscope. Serious complications rarely occur from colonoscopy.
The physician can answer any questions the patient has.
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