What is a
colonoscopy?
Gastroenterologists use colonoscopy to
screen for colorectal cancer. This minimally
invasive endoscopic procedure enables
doctors to examine the lining of a patient’s
rectum and large intestine (colon) for
abnormalities.
When they perform a colonoscopy,
gastroenterologists pass an endoscope or
colonoscope (i.e., a thin and flexible tube
with a light and camera on the leading end)
through a patient’s rectum and into the colon.
Doctors then carefully examine the lining of
the patient’s colon for polyps or any other
abnormalities. If any polyps are detected,
they remove them using a small snare that’s
attached to the endoscope/colonoscope.
Most colorectal cancer can be prevented by
removing these polyps.
In addition to using this procedure to
screen people for colorectal cancer,
gastroenterologists use colonoscopy to
evaluate patients who have colorectal
bleeding, abdominal pain and chronic
diarrhea. This is known as a diagnostic
colonoscopy.
Gastroenterologists also perform surveillance
colonoscopies to examine patients who have
had colon polyps removed in the past.
Why it is crucial to get screened for
colorectal cancer?
Some 130,000 Americans are diagnosed with
colorectal cancer (cancer of the colon or rectum)
every year — and nearly 50,000 of them die from the
disease. Colorectal cancer is the second leading cause
of cancer deaths in the U.S. behind lung cancer, yet
more than 30 percent of the adults in this country
aren’t getting screened for this disease.
The good news is that colorectal cancer has a 90
percent survival rate when it’s detected early enough. In
fact, gastroenterologists can detect this disease in a
person before they exhibit any symptoms. It has been
estimated that greater colorectal cancer awareness
and screening could save at least 30,000 lives in the
U.S. each year.
Current national guidelines recommend that every
man and woman (who get the disease in equal
numbers) should be screened for colorectal cancer as
soon as they turn 45 — even if they haven’t exhibited or
experienced any problems or symptoms.
Patients who are under 45 and have high-risk conditions
may need to get screened for colorectal cancer on a
more regular basis. High-risk conditions include:
- Family history of colorectal cancer or precancerous
polyps in a first degree relative diagnosed before age 60
- Multiple first-degree relatives with colorectal cancer
or precancerous polyps
- Family history of inherited colorectal cancer syndrome
- Previous diagnosis of ulcerative colitis or Crohn's disease
Patients should talk to their primary care physician or
gastroenterologist about the need to get screened for
colorectal cancer.
Why is colonoscopy the optimal
colorectal cancer screening option?
There are several ways physicians screen their patients
for colorectal cancer, including colonoscopy, flexible
sigmoidoscopy, fecal immunochemical (FIT) or stool
tests and MT-sDNA (Cologuard) or virtual tests.
Colonoscopy is the only test to prevent colorectal
cancer, with its unique ability to remove polyps before
they turn into cancer. It is the only screening test
recommended at 10-year intervals, because it’s by
far the best test at finding precancerous polyps. This
is important because far more invasive treatments like
surgery and/or chemotherapy are required once colorectal
cancer develops. Plus, a colonoscopy is still required if a
stool test or CT scan flags any abnormalities.
How long does a colonoscopy take?
Colonoscopies are generally performed on an
outpatient basis that takes about 30 to 45 minutes
to complete. In some cases, patients are given a
mild sedative that enables them to relax and make
them sleepy during the procedure to minimize any
discomfort — which can include abdominal pressure,
bloating or cramping. In other cases, patients receive
an anesthetic that puts them completely asleep during
the procedure.
Do colonoscopies ever have
complications?
Colonoscopy is a common outpatient procedure.
It does not require hospitalization. Complications
from a colonoscopy are rare, but they can occur.
This includes a perforation (i.e., a hole or tear) in
the gastrointestinal tract lining, which may require
emergency surgery. If a biopsy is taken or a polyp is
removed during a colonoscopy, bleeding may occur.
This bleeding is usually minor, and it normally stops
on its own, but it can require additional treatment. A
patient’s heart rate, blood pressure or breathing may
also change because of the medications that are used
to perform a colonoscopy. So while complications after
a colonoscopy are uncommon, patients should not
hesitate to contact their doctor immediately if they
experience any complications following a colonoscopy,
including running a fever or abdominal pain or
bleeding or black stools.
What happens if the doctor finds polyps
or other abnormalities?
It is not unusual for gastroenterologists to find growths
or polyps on the lining of a patient’s colon when
they perform a colonoscopy. These polyps come in
different shapes and sizes. Because most polyps are
pre-cancerous — which means they can develop into
colorectal cancer — gastroenterologists generally
remove them on the spot using a tiny wire loop that is
called a snare, although patients may be referred to a
specialist to remove polyps that are unusually large.
Most polyps are typically sent to the pathologist to be
checked if they are precancerous or not.
If a gastroenterologist discovers any other
abnormalities while they are performing a colonoscopy,
they can pass a tiny device through the endoscope/colonoscope to obtain a tissue sample for testing
(i.e., biopsy). These devices are also sometimes used to
remove polyps.
When a gastroenterologist performs colonoscopy
on a patient who is bleeding from the colon, they may
inject medications into the affected area. They may
stop the bleeding using a heat treatment that is known
as cauterization, or they may apply small metal clips
to the affected blood vessels. These procedures are
usually not painful.
Colonoscopy is the optimal way to prevent colorectal
cancer because it allows gastroenterologists to fi nd and
remove polyps on the spot.
What are patients required to do before
a colonoscopy?
Patients are generally limited to a clear liquid diet (e.g.,
gelati n) the day before they have a colonoscopy. They also
need to undergo a bowel preparation process that will
empty and clean their colon the evening before the exam.
There are now various ways of doing bowel preparation,
including consuming lower amounts of the solution or
taking pills, making the process more agreeable for many.
This process takes a few hours, and it is the only way to
ensure that a gastroenterologist can examine a patient’s
colon in a full and comprehensive way.
Patients can continue to take most of their normal
medications before a colonoscopy, although some are
known to interfere with the bowel preparation process
or the safety of the procedure. Patients are consequently
encouraged to let their gastroenterologist know about any
medications they take, especially insulin or other diabetes
medications, aspirin products, arthritis medications, blood
thinners (e.g., warfarin, apixaban, rivaroxaban, heparin,
etc.) and other drugs that interfere with clotting (e.g.,
clopidogrel/Plavix, ticagrelor, prasugrel, etc.). Patients
should not take over-the-counter medications and
supplements on the morning of the procedure.
Patients are also encouraged to let their gastroenterologist
know about any medical conditions they have, including
heart or kidney or lung disease. And, they should tell their
doctor if they are allergic to any medications or latex.
Finally, it is essential for patients to follow their doctor’s
instructions before and after they have a colonoscopy.
What happens after a colonoscopy?
Following a colonoscopy, patients are free to go
home once most of the effects of any medication or
anesthesia have worn off , although they will be required
to have a family member or friend drive them home.
Patients should also not drive or operate machinery
or make legal decisions on the day of the procedure
— even if they feel alert after the procedure, as the
medications that are used for colonoscopy can affect
one’s judgment and reflexes for the rest of the day.
Some patients experience mild discomfort, bloating or
pass gas because of the air that is introduced during the
examination. Those symptoms usually go away within
a day. Patients can also resume their usual diet once
the exam is done unless their doctor instructs them to
do otherwise. Gastroenterologists normally share the
preliminary results of the procedure with their patient
on the day of the exam, but the results of some tests
like biopsies may take several days.
How often a patient needs their next colonoscopy
depends on several factors, which include:
- How clean their colon was during the procedure (i.e.,
whether the doctor was able to conduct a full and
comprehensive exam)
- How many pre-cancerous polyps were removed
- The size of the largest polyp that was removed
- Whether any of the polyps that were removed had
any troubling features (e.g., early cancer)
Once gastroenterologists have this information, they
will recommend when the patient should get their next
colonoscopy (normally the next three, five or 10 years).
How to find a gastroenterologist in
your community
Patients who need to schedule a colonoscopy can
visit ASGE.org/FindADoctor to fi nd an ASGE member
gastroenterologist in your community who has received
specialized training in performing this procedure.
Important Reminder: This information is intended only to provide general guidance. It does not provide definitive medical advice. It is very important that you consult your doctor about your specific condition.