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BARIUM ENEMA - a patient's guide
Dr David Hough - Radiologist
What is it and what is it used for?
The barium enema is an examination of the colon, or large
bowel, looking for abnormalities such as diverticula, polyps
and cancer. It is generally done because of symptoms such
as pain, bleeding and altered bowel habit, but it may also
be done as a screening test, for example in patients with
a strong family history of bowel cancer.
Who can have a barium enema?
Because the test utilizes x-rays, it should not be performed
on pregnant patients. Anyone else may safely undergo barium
enema. Difficulties may be encountered in patients who have
very poor mobility, but the examination can be modified
to accommodate such patients.
How much radiation exposure is there?
An average barium enema will result in a dose equivalent
of approximately 13mSv. To put this into perspective, the
average background radiation dose in New Zealand is 2mSv
per year. This is the dose that the average person receives
from the environment each year. In some populated parts
of the world the background radiation is more than 10 times
higher, with no detectable increase in cancer incidence.
The dose from a barium enema is considered to be safe.
Before the enema
Your bowel must be clean prior to the examination, as any
faeces remaining in the colon makes an accurate interpretation
difficult. You will be provided with a prescription and
detailed dietary instructions prior to the enema. The bowel
preparation generally consists of a special low residue
diet for 24 hours, and ingestion of a bowel cleansing liquid
the night before the enema. A Dulcolax suppository will
also be needed the morning of the enema.
What happens during the examination?
The examination is performed by a radiologist who is a
medical doctor with specialist training in x-ray examinations.
You will be asked to lie on a table that has an x-ray tube
and filming device attached. The radiologist may need to
do a rectal examination prior to the enema. A tube is then
inserted into the rectum, either by the radiographer or
radiologist. A small balloon is inflated at the tip of the
tube, to prevent the tube from falling out. The tube is
connected to a bag containing a suspension of barium.
Barium has a high density, and is visible on x-ray pictures.
Barium is not radioactive. The most common type of barium
enema is the double-contrast enema. In this, barium is introduced
into the lower part of the bowel, followed by air. You will
be asked to roll into different positions to allow the barium
and air to get all the way around the colon. The table also
tilts to assist in this. A number of x-ray pictures will
be taken of each part of the colon. Sometimes an injection
is necessary to prevent or overcome bowel spasm. The films
are subsequently examined by the radiologist, and a report
sent to the referring doctor.
In some cases a single contrast barium enema is preferable
to the double contrast type. This utilizes a dilute barium
suspension and no air. Less rolling from side to side is
required, and this test may be more suitable in patients
with poor mobility.
Will it hurt?
Many people are needlessly apprehensive of the enema. Generally
there should be only mild discomfort, due to distention
of the colon with air. The bowel preparation is generally
the most unpleasant part of the whole test, and anyone who
completes the preparation should have no problem with the
enema. As the test is not painful, painkillers are not given.
The barium enema has an excellent safety record, with an
extremely low risk of bowel perforation. The risk is much
lower than that of colonoscopy, another bowel examination
with which the barium enema is frequently compared.
After the enema
A bloated sensation may persist for several hours after
the enema. Your diet may return to normal immediately, and
you should drink plenty of liquid. You will pass the barium
over the next few days.
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