Encyclopedia of Health and Medicine

colonoscopy 27
mize discomfort and anxiety. The procedure takes
30 to 45 minutes, with another one to two hours
to recover from the sedation.
Preparation Most people find the preparation
for colonoscopy, which consists of cleansing the
gastrointestinal tract, the most unpleasant aspect
of the procedure. The preparation for virtual
colonoscopy requires the same bowel-cleansing
procedure as does conventional colonoscopy.
Completing the preparation for colonoscopy is
essential for optimal results, however. It typically
includes
• no aspirin or aspirin products (to reduce the
risk for bleeding) and no iron supplements or
products (iron darkens tissue) for five days
before the colonoscopy
• no nuts, seeds, grapes, peas, beans, or tomatoes
for three days before the colonoscopy (particles
from these foods lodge in the folds of the intestinal
mucosa)
• no NONSTEROIDAL ANTI-INFLAMMATORY DRUGS
(NSAIDS) for five to seven days before the
colonoscopy (to reduce the risk for bleeding)
• only clear liquids for 24 hours before the
colonoscopy
• at midday the day before the colonoscopy, the
bowel-cleansing process begins with the drinking
of a laxative solution consumed at the rate
of eight ounces every 10 minutes for a total
consumption of one gallon of the solution
The laxative prep results in bowel movements
that start about an hour after beginning to drink
the solution and continue for about eight hours.
Drinking the solution often causes NAUSEA. Keeping
the solution as cold as possible (even surrounding it
with ice in the refrigerator) and chewing gum or
sucking on hard candy between glasses can help. It
is necessary to drink the entire gallon of the solution
to completely clear the gastrointestinal tract.
Fecal remnants in the colon can obscure the wall of
the bowel, limiting the ability of the gastroenterologist
to visualize the entire colon. Most gastroenterologists
will not proceed with the colonoscopy if
the preparation is incomplete.
Procedure The person lies on his or her left
side on a narrow bed, with the knees flexed. After
initiating intravenous sedation, the gastroenterologist
gently inserts the lubricated colonoscope into
the anus. A small pump injects air ahead of the
scope, opening the colon so the gastroenterologist
can advance it into the colon. The examination of
the colon takes about 20 minutes, longer when
there are polyps for the gastroenterologist to
remove or biopsy. Some people feel pressure with
the injection of air or when the scope rounds the
corners of the colon. However, most people feel
little discomfort and cannot recall the procedure
when it is over.
Recovery Following conventional colonoscopy,
the person rests in a recovery area until the sedative
wears off, usually within an hour or two, and
then may go home. Doctors recommend resting
quietly for the remainder of the day, which is
what most people feel like doing. There is usually
no discomfort after the procedure, aside from an
accumulation of intestinal gas until regular eating
returns the gastrointestinal tract to normal function.
The gastroenterologist receives the pathologist’s
analysis of any tissues removed within about
a week. Following virtual colonoscopy, the person
may go home immediately after the procedure.
Risks and Complications
Complications related to conventional colonoscopy
are very rare but may include perforated
bowel (which requires emergency surgery to
repair), INFECTION, and bleeding from removed or
biopsied polyps.
Virtual Colonoscopy
Virtual colonoscopy, a procedure that allows noninvasive
visualization of the gastrointestinal tract,
became available in the late 1990s. Virtual
colonoscopy, correctly called computed tomography
colonography or CT colonography, uses COM-
PUTED TOMOGRAPHY (CT) SCAN to examine the colon
with nearly the same accuracy as conventional
colonoscopy but without the need for sedation or
to enter the body.
The significant drawback to CT colonography is
that it allows only viewing of the colon, not
biopsy or polypectomy. The gastroenterologist
must still use conventional colonoscopy to remove
detected intestinal polyps or to biopsy suspicious
growths. The preparation for virtual colonoscopy