These summaries were prepared by Dr Felicity Goodyear-Smith, Goodfellow Unit, Department
of General Practice & Primary Health Care, The University of Auckland. Thanks
for the material provided by Ms Sarah Marshall, Charge Nurse Manager, Department
of Gastroenterology & Hepatology, A+, Auckland.
Colonoscopy
About Colonoscopy
Endoscopic examination of the lower bowel: Colonoscopy and Sigmoidoscopy
Description of procedure
Fibreoptic colonoscopic examination allows an accurate internal inspection of the
large bowel from anus and rectum through the colon to the caecum or even into the
lower end of the small intestines. The flexible sigmoidoscope is a shorter instrument
which allows inspection only of the lower part of the large bowel. This instrument
has largely replaced rigid sigmoidoscopes and proctoscopes. While early colonoscopes
merely carried a light source, these days the instrument usually contains a videocamera
allowing inspection of the bowel via a video monitor or even transmitted using communication
technology to a distant location. The colonoscope allows for other instruments to
be passed through it to carry out certain procedures for better diagnosis or treatment.
In particular, it allows for painless biopsy for diagnostic or treatment purposes,
and removal of polyps using electrocautery. Conditions that might be diagnosed by
use of the colonoscope include bowel carcinomas, polyps, colitis (ulcerative or
Crohn's), diverticulosis and diverticulitis, and bleeding lesions sited in the colon
or rectum.
Advantages of Colonoscopy:
- Safe and highly effective diagnostic technique
- More accurate than barium enema
- Simpler than exploratory surgery
Disadvantages of Colonoscopy:
- Most surveys report complications in 1 of every 1000 examinations or less. Possible
complications include bowel perforation or haemorrhage, which might require surgical
repair or blood transfusion respectively.
- Risk of perforation or haemorrhage is increased when polyps are removed via the
endocsope.
- The procedure requires a hospital stay (usually on an out-patient basis).
- Sedation is required, with a small risk of adverse reactions to medications used.
- There is a degree of patient discomfort.
- There is a very small risk of contracting hepatitis, the AIDS virus or disease-causing
bacteria and viruses, should there be inadequate cleaning and disinfection of the
instrument after each use.
Reasons patients might be referred for Colonoscopy:
- Bleeding from the lower bowel
- Abdominal symptoms, such as pain or discomfort, particularly if associated with
weight loss or anaemia
- Chronic diarrhoea, constipation, or a change in bowel habit
- Abnormalities found on other tests eg on a barium enema x-ray examination
- Screening and surveillance: periodic colonoscopy can be used to monitor patients
with previous polyps, colon cancer, or a family history of colon cancer
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Images from Colonoscopy
Click on these images for an enlarged view - opens in a separate window which you
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Patient Information
This patient information is
available as a PDF file from which you may print copies - you will need
an acrobat reader.
Information for the patient on Colonoscopy
"Colonoscopy" means looking inside the colon (also called large intestine or large
bowel). The colon is the last portion of your digestive tract. It starts at the
caecum, which attaches to the end of the small intestine, and ends at the rectum.
The colon is a hollow tube, about one and a half metres long, and its main function
is to store unabsorbed food products prior to their elimination.
The colonoscope is a long, thin, flexible tube with a tiny video camera and a light
on the end which can be guided up the large bowel giving a detailed view of the
bowel lining onto a video monitor.
The diagram of the colon (large intestine or large bowel) illustrates the approximate
path the colonoscope takes during a colonoscopy. The colonoscope is shown as a solid
"orange" line starting at the rectum (at the bottom of the diagram) and finishing
in the area of the caecum.
Problems can be easily seen and treatment can be given immediately using tiny surgical
instruments passed through the internal channels of the colonoscope. These can be
used to painlessly remove growths, cauterise bleeding blood vessels or to collect
tiny pieces of tissue (biopsy) for analysis under the microscope.
Preparation
The large intestine requires a thorough cleansing before colonoscopy to allow a
clear view of the bowel lining. This means the bowel must be completely free of
all solid waste. To achieve this you will be given a special diet and laxatives
to use the day before your test. The actual regime varies from centre to centre.
You will be given instructions on what you need to do by staff from the endoscopy
centre, which you must follow carefully. You will be given a list of foods you are
permitted to eat (and those that are forbidden) for 3 days before the investigation.
The bowel preparation is a safe regimen and generally involves drinking several
litres of a fluid which induces diarrhoea and thoroughly cleanses the lining of
the bowel. Some centres use laxative tablets or enemas to help in the cleansing
process. Once you have taken the preparation fluid you will be required to fast
(have nil by mouth) or have clear fluids only until after the procedure.
Risks and Potential Complications
For inspections of the bowel alone, complications are uncommon. Most surveys report
complications in 1 of every 1000 examinations or less.
Perforation (making a hole in the bowel) or major bleeding from the bowel is extremely
rare but if it occurs, may require an operation. When polyps are removed during
the examination there is a slightly higher risk of perforation or bleeding. In the
unlikely event of haemorrhage occurring, a blood transfusion may be necessary. If
you wish to know full details of rare complications, before the procedure you should
indicate your wish to fully discuss these with the doctor.
Other Considerations:
- Please keep your appointment if at all possible. Because of the preparation required
for the investigation, your appointment cannot be used by someone else if you cancel
just before your scheduled time or if you fail to attend.
- Colonoscopy is usually conducted under sedation. You will be relaxed but awake and
able to co-operate with instructions when needed.
- You are not able to drive or operate machinery for 8 hours after the procedure,
so please have transport organised to get you home.
- Elderly patients undergoing colonoscopy are advised to have a support person who
transports them home and stays with them for several hours.
- Because air may have been placed in your colon to improve the view obtained through
the colonoscope, you may experience mild discomfort for several hours until you
have passed the gas.
- Although you can return to your normal diet, eat lightly at first, increasing your
intake of food as tolerated.
- Because of the sedation you have received, you should not drink alcohol for the
remainder of the day.
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