Colorectal Cancer Info > ColonoscopyColonoscopy (biopsy and polyp removal)
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 | Reasons for the Exam | Preparation | Procedure | Results
Benefits | Alternatives | Side Effects and Risks | Summary
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 these 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. A patient's medical history,
physical exam, laboratory tests and x-rays can provide information useful in
making a diagnosis. However, 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 - 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
Preparation
To obtain the full
benefits of the exam, the colon must be clean and free of stool. The patient
will receive instructions on how to do this. It 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 physician will advise the patient regarding the use of regular medications
during that time.
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 the ployp. 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 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
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 further analysis
may not be 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 directly
and accurately to stop the bleeding. Other treatments can be given through the
endoscope when necessary.
Alternatives
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 hospitalization and, rarely, surgery. Quite uncommonly a diagnostic
error or oversight may occur.
Due to the mild sedation, someone must be available to drive the patient
home. The driver may leave, but must be available by mobile phone. The patient
should not drive or operate machinery following the exam.
Summary
Colonoscopy is an outpatient
exam that is performed with the patient lightly sedated. The procedure provides
significant information used to diagnose a colon condition and determine which
specific treatment should 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 may have.