simple>
Advantages of this test " Colonoscopy finds most small polyps and almost all large polyps and cancers. If found, polyps can be removed right away.Drawbacks to this test " Colonoscopy has more risks than the other screening tests. In 1 in 1,000 people, it can cause bleeding or tear the inside of the colon. Cleaning out the bowel beforehand can be unpleasant. Plus, people usually cannot work or even drive themselves home the day of the test, because of the relaxation medicine they must take during the test.Sigmoidoscopy " A sigmoidoscopy is very similar to a colonoscopy. The difference is that this test looks only at the last part of the colon, and a colonoscopy looks at the whole colon. Before you have a sigmoidoscopy, you must clean out the lower part of your colon using an enema. This bowel cleaning is not as thorough or unpleasant as the one for colonoscopy. For this test, you do not need to take medicines to help you relax, so you can drive and work afterward if you want.- Advantages of this test " Sigmoidoscopy can find polyps and cancers in the rectum and the last part of the colon. If polyps are found, they can be removed right away.
- Drawbacks to this test " In about 2 out of 10,000 people, sigmoidoscopy tears the inside of the colon. The test also can't find polyps or cancers that are in the part of the colon the test does not view (figure 3). If doctors find polyps or cancer during a sigmoidoscopy, they usually follow up with a colonoscopy.
CT colonography (also known as virtual colonoscopy or CTC) " CTC looks for cancer and polyps using a special X-ray called a "CT scan. " For most CTC tests, the preparation is the same as it is for colonoscopy.- Advantages of this test " CTC can find polyps and cancers in the whole colon without the need for medicines to relax.
- Drawbacks to this test " If doctors find polyps or cancer with CTC, they usually follow up with a colonoscopy. CTC sometimes finds areas that look abnormal but that turn out to be healthy. This means that CTC can lead to tests and procedures you did not need. Plus, CTC exposes you to radiation. In most cases, the preparation needed to clean the bowel is the same as the one needed for a colonoscopy. The test is expensive, and many insurance companies do not cover this test for screening.
Stool test for blood " "Stool " is another word for bowel movements. Stool tests most commonly check for blood in samples of stool. Cancers and polyps can bleed, so blood will show up in the stool. Other less serious conditions can also cause small amounts of blood in the stool, and that will show up in this test. You will have to collect small samples from bowel movements, which you will put on a special card and mail to your doctor or to a lab.- Advantages of this test " This test does not involve cleaning out the colon or having any procedures.
- Drawbacks to this test " Stool tests are less likely to find polyps than other screening tests. These tests also often come up abnormal even in people who do not have cancer. If a stool test shows something abnormal, doctors usually follow up with a colonoscopy.
Stool DNA test " The stool DNA test checks for genetic markers of cancer, as well as for signs of blood. For this test, you collect a whole bowel movement and ship it " on ice " to a lab.- Advantages of this test " This test does not involve cleaning out the colon or having any procedures. When cancer is not present, it is less likely to be falsely abnormal than a stool test for blood. That means it leads to fewer unnecessary colonoscopies.
- Drawbacks to this test " This test was approved for use in August 2014. That means it will be a while before it is widely available and it is not clear how it will be covered by insurance or medicare. It also means doctors do not yet know a lot about how it compares to other screening tests. It might be unpleasant to collect and ship a whole bowel movement. If a DNA test shows something abnormal, doctors usually follow up with a colonoscopy.
How do I choose which test to have? " Work with your doctor or nurse to decide which test is best for you. Being screened " no matter how " is more important than which test you choose.
Some doctors prefer tests that can find polyps that could turn into cancer. These include colonoscopy, CT colonography, and sigmoidoscopy.
Who should be screened for colon cancer? " Doctors recommend that most people begin having colon cancer screening at age 50. People who have an increased risk of getting colon cancer sometimes begin screening at a younger age. That might include people with a strong family history of colon cancer, and people with diseases of the colon called "Crohn's disease " and "ulcerative colitis. "
Most people can stop being screened around the age of 75, or at the latest 85.
How often should I be screened? " That depends on your risk of colon cancer and which test you have.
Most people can choose one of these schedules:
- Colonoscopy every 10 years
- Computed tomography (CTC) every 5 years
- Sigmoidoscopy every 5 years
- Stool testing for blood once a year
- Stool DNA testing every 3 years (but doctors are not yet sure of the time frame)
People who have a high risk of colon cancer often need to be tested more often and should have a colonoscopy.
All topics are updated as new evidence becomes available and our peer review process is complete.
This topic retrieved from UpToDate on: Nov 04, 2014.
Topic 16186 Version 5.0
Release: 22.8 - C22.208
© 2014 UpToDate, Inc. All rights reserved.
figure 1
Digestive system
This drawing shows the organs in the body that process food. Together these organs are called "the digestive system," or "digestive tract. " As food travels through this system, the body absorbs nutrients and water.
Graphic 66110 Version 4.0
View Originalfigure 1
Digestive system
This drawing shows the organs in the body that process food. Together these organs are called "the digestive system," or "digestive tract. " As food travels through this system, the body absorbs nutrients and water.
Graphic 66110 Version 4.0
View Original
figure 2
Colonoscopy
During a colonoscopy, you lie on your side and the doctor or nurse puts a thin tube with a camera into your anus (from behind). Then the doctor or nurse advances the tube into the rectum and colon. The camera sends video pictures from inside your colon to a television screen.
Graphic 52258 Version 4.0
View Originalfigure 2
Colonoscopy
During a colonoscopy, you lie on your side and the doctor or nurse puts a thin tube with a camera into your anus (from behind). Then the doctor or nurse advances the tube into the rectum and colon. The camera sends video pictures from inside your colon to a television screen.
Graphic 52258 Version 4.0
View Original
figure 3
Colonoscopy versus sigmoidoscopy
During a colonoscopy or a sigmoidoscopy, you lie on your side, and the doctor or nurse puts a thin tube with a camera into your anus (from behind). Then the doctor or nurse advances the tube into the rectum and colon. The camera sends video pictures from inside your colon to a television screen.
A colonoscopy allows the doctor to see the whole colon (shown in pink and green). A sigmoidoscopy allows the doctor to see only the last part of the colon (shown in green).
Graphic 58734 Version 4.0
View Originalfigure 3
Colonoscopy versus sigmoidoscopy
During a colonoscopy or a sigmoidoscopy, you lie on your side, and the doctor or nurse puts a thin tube with a camera into your anus (from behind). Then the doctor or nurse advances the tube into the rectum and colon. The camera sends video pictures from inside your colon to a television screen.
A colonoscopy allows the doctor to see the whole colon (shown in pink and green). A sigmoidoscopy allows the doctor to see only the last part of the colon (shown in green).
Graphic 58734 Version 4.0
View Original
Consumer Information Use and Disclaimer
This information is not specific medical advice and does not replace information you receive from your health care provider. This is only a brief summary of general information. It does NOT include all information about conditions, illnesses, injuries, tests, procedures, treatments, therapies, discharge instructions or life-style choices that may apply to you. You must talk with your health care provider for complete information about your health and treatment options. This information should not be used to decide whether or not to accept your health care providers advice, instructions or recommendations. Only your health care provider has the knowledge and training to provide advice that is right for you.The use of UpToDate content is governed by the UpToDate Terms of Use. ©2014 UpToDate, Inc. All rights reserved.
Copyright
© 2014 UpToDate, Inc. All rights reserved.