Download Colonoscopy vs. Sigmoidoscopy FAQ

Colonoscopy vs. Sigmoidoscopy FAQ
The relative merits of colonoscopy versus sigmoidoscopy in colon cancer screening has been a
source of ongoing debate. The July issue of The New England Journal of Medicine featured two
articles and an editorial suggesting that colonoscopy is superior to flexible sigmoidoscopy as a
colon cancer screening method. However, experts worry that the articles send the wrong message.
That people get regular screening of some sort is more important than what screening tests are
used, they say.
What the Studies Found
The difference between colonoscopy and sigmoidoscopy is related to which parts of the colon each
can examine. Sigmoidoscopy allows doctors to view only the lower part of the colon, while
colonoscopy allows doctors to view both the upper and lower sections.
The two studies had similar results:
Roughly half of the patients with upper colon abnormalities did not have abnormalities in the lower
colon.
Between one percent and three percent of patients with no abnormalities in the lower colon had
problems in the upper colon.
These studies suggest that colonoscopy is superior to sigmoidoscopy because patients with upper
colon abnormalities may slip through the cracks if sigmoidoscopy were the only screening tool.
However, doctors do not traditionally use sigmoidoscopy alone, as they did in this study. Instead,
sigmoidoscopy is usually combined with a procedure called a fecal occult blood test (FOBT), which
detects trace amounts of blood in the stool and can detect cancers forming throughout the colon.
For this reason, these studies may not reflect the actual accuracy of the screening that most people
receive. "The more valid and relevant comparison is colonoscopy vs. sigmoidoscopy with FOBT,"
says Miriam Komaromy, Genetic Health's vice president of clinical services.
The Importance of Regular Screening
Colon cancer is one of the most common cancers in American men and women. More than 100,000
new cases are diagnosed each year. The timing of detection is critical. For the one third or so new
cases found in the early stages, 90 percent of the patients live at least 5 years after the diagnosis and
many live much longer. For the patients with cancer that has reached local lymph nodes and nearby
organs, only 65 percent live at least 5 years beyond diagnosis. For patients with cancer that has
spread to distant parts of the body such as the liver or lungs, the five-year survival rate drops to
below 10 percent. With these odds, it's important that people catch colon cancer in its early stages.
Currently, the American Cancer Society and the American College of Gastroenterology recommend
the following screening regimens for people at average risk for colon cancer, beginning at age 50.
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FOBT every year plus sigmoidoscopy every 5 years
Colonoscopy every 10 years
More on Screening Recommendations for People in the General Populations
More on Screening Recommendations for People With Familial Colon Cancer
More on Screening Recommendations for People With HNPCC
More on Screening Recommendations for People With FAP
Screening in the Real World
Few gastroenterologists would dispute that colonoscopy is the best test to use for colon cancer
screening, according to Jonathon Terdiman, clinical director of the UCSF Colorectal Cancer
Prevention Program. However, he also says that FOBT plus sigmoidoscopy is not a bad option,
particularly because of how impractical it can be to use colonoscopy as a general screening method.
Few specialists are allowed to perform the procedure (in U.S., only about 10,000 specialists for 50
to 70 million patients) and HMOs and other third party payers do not routinely cover colonoscopy.
The procedure is also uncomfortable and many people find it embarrassing, which can prevent
people from having regular screening. Sigmoidoscopy, on the other hand, is quicker and less
expensive than colonoscopy, and is more regularly covered by HMOs.
Komaromy stresses that the major concern isn't what screening method a person uses, it's that the
people who need screening get it. She says that only half of her patients who should be screened
actually get regular screening of any kind. In general, only about 30 percent of the population for
whom screening is recommended get screened. "We need to focus on encouraging people to get
regular screening, regardless of which screening method is the best."
Colonoscopy vs. Sigmoidoscopy FAQ
What is colonoscopy?
Colonoscopy (ko-lun-AH-skuh-pee) is an exam that lets a doctor closely look at the inside of the
entire colon and rectum. The doctor is looking for polyps (pah-lips) or signs of cancer. Polyps are
small growths that over time can become cancer. The doctor uses a thin (about the thickness of a
finger), flexible, hollow, lighted tube that has a tiny video camera on the end. This tube is called a
colonoscope (ko-LAHN-uh-scope). The colonoscope is gently eased inside the colon and sends
pictures to a TV screen. Small amounts of air are puffed into the colon to keep it open and let the
doctor see clearly.
The exam itself takes about 30 minutes. Patients are usually given medicine to help them relax and
sleep while it’s done.
Your doctor decides how often you need this test, usually once every 10 years, depending on your
personal risk for colon cancer. It’s important for you to talk with your doctor to understand your
risk for colon cancer, the guidelines you should follow for testing, and whether you need to start
having the tests at age 50 or earlier.
What is sigmoidoscopy?
During sigmoidoscopy (sig-moid-AH-skuh-pee), a doctor closely looks only at the lower part of the
colon and the rectum for signs of cancer or polyps (pah-lips). (Because the scope used is only about
2 feet long, the doctor is able to see the entire rectum but less than half of the colon with this exam.)
Polyps are small growths which can over time become cancer. The doctor uses a thin (about the
thickness of a finger), flexible, hollow, lighted tube that has a tiny video camera on the end. This
tube is called a sigmoidoscope (sig-MOID-uh-scope). The sigmoidoscope is gently eased inside the
colon and sends pictures to a TV screen. Small amounts of air are puffed into the colon to keep it
open and let the doctor see clearly.
The exam takes 10 to 20 minutes. The patient usually doesn’t need medicine, but this might be an
option you can talk about with your doctor.
Your doctor decides how often you need this test, usually once every 5 years, depending on your
personal risk for colon cancer. It’s important for you to talk with your doctor to understand your
risk for colon cancer. You will want to be sure about the guidelines you should follow for testing,
and whether you need to start having tests at age 50 or earlier.
Will it hurt?
No, these exams are usually not painful. Patients are given medicine to make them sleep through a
colonoscopy, so they don’t feel anything. Medicine isn’t needed for a sigmoidoscopy.
During both of these tests, air is pumped into the cleaned-out colon to keep it open so that doctors
can get the best pictures. The air pressure may cause some discomfort and cramping, but it should
not hurt.
As with most medical tests, complications are possible with both of these tests. Some can be serious
— for instance, bleeding and puncture of the colon — but they are very uncommon. Make sure you
understand how these tests work, how you can expect to feel during the test, and possible problems
that may come up.
Who will do the exam?
Colonoscopy is almost always done by a doctor, usually a gastroenterologist (a doctor whose
specialty is the digestive tract) or a surgeon.
Sigmoidoscopy exams are often done by primary care doctors (general practitioners, family
doctors, and internal medicine doctors) in their offices. Studies show that a well-trained clinical
nurse specialist, nurse practitioner, or physician’s assistant can do sigmoidoscopies very well too.
Will I be in a private room?
Colonoscopy is done in a private area; it may be a hospital outpatient department, a clinic, an
ambulatory surgery center, or a doctor’s office. The patient’s privacy is very important. If you have
concerns, talk with the doctor about where and how the procedure will be done.
Sigmoidoscopy typically is done in a private room, with no other patients nearby. Doctors and nurse
specialists are professional and very careful to respect the patient’s privacy.
How do I prepare? Will I need to miss work?
Preparation for colonoscopy or sigmoidoscopy makes you to go the bathroom a lot! Your doctor will
give you instructions. Read them carefully a few days ahead of time, since you may need to shop for
special supplies and get laxatives or enemas from a pharmacy.
You may also need to change your plans for the preparation day. You will need to be near your
bathroom as soon as you start the laxatives. If any of the instructions are not clear or you do not
understand them, call the doctor’s office and go over them step by step with the nurse.
Many people consider the bowel preparation (often called the bowel prep) the worst part of these
tests. You may need to follow a special diet for one or more days before these exams and take very
strong laxatives before both procedures. You may also need enemas to clean out your colon. In
order for the doctor to see the inside of your rectum and colon clearly and get good pictures, your
bowels need to be as cleaned out as possible.
Because colonoscopy is usually done with drugs that make you sleepy, most people miss work the
day of the test. Ask your doctor if you’ll need to miss work for a sigmoidoscopy. For either test you’ll
need to stay close to a bathroom the day before and the morning of the test. You might want to
schedule the test the day after a regularly scheduled day off, so you can be at home the day before
without taking an extra day off.
How will I feel afterward? Will I need someone to drive me home?
Most people feel OK after a colonoscopy. They may feel a bit woozy from the drugs (anesthesia).
They’ll be watched as they wake up. They may have some gas, which could cause mild discomfort.
Because of the medicines given for the test, most places will not let you drive, so you will need
someone to take you home.
After a sigmoidoscopy, you get up and walk out. There should be no problem driving yourself home,
as long as you have not had any drugs to make you sleepy during the test.
What if they find something?
If a small polyp is found, your doctor will probably remove it. Over time some polyps could become
cancer. If your doctor sees a large polyp, a tumor, or anything else abnormal, a biopsy (by-op-see)
will be done. For the biopsy, part or all of the polyp or abnormal area is taken out through the
colonoscope or sigmoidoscope. It’s sent to a lab to be checked under a microscope for cancer or precancer cells.
If a polyp or colorectal cancer is found during sigmoidoscopy, you will need to have a colonoscopy
later to check for polyps or cancer in the rest of your colon.
Why are these tests so important?
Colorectal cancer screening helps people stay well and saves lives. Regular colorectal cancer testing
is one of the most powerful weapons for preventing colorectal cancer or finding it early, when it is
easier to treat. The screening tests available can be divided into 2 broad groups:
Tests that mainly find cancer: These involve testing the stool (feces) for signs that cancer may be
present. These tests are less invasive and easier to have done, but they are less likely to detect
polyps.
Tests that can find both colorectal polyps and cancer: These tests look at the structure of the colon
itself to find any abnormal areas. Colonoscopy and sigmoidoscopy fall in this group, along with
double-contrast barium enema and CT colonography (virtual colonoscopy). These tests are
preferred if they are available and you are willing to have them.
Removing polyps can help prevent colorectal cancer from ever starting. And cancers found in an
early stage, while they are small and before they have spread, are more easily treated. Nine out of
10 people whose colon cancer is discovered early will be alive 5 years later. And many will live a
normal life span.
But all too often people don’t get any of these screening tests. Then the cancer can grow and spread
without being noticed, like a silent invader. Early on, colorectal cancer doesn’t usually have
symptoms. In most cases, by the time people do have symptoms the cancer is advanced and very
hard to treat.
Regular screening is necessary to find these cancers in the early stages. Ask a doctor about the best
screening plan for you.
Sources: Genetic Health (www.GeneticHealth.com) and American Cancer Society (www.Cancer.org).