What is a Colonoscopy Screening?
A colonoscopy (koh-luh-NAH-skuh-pee) screening is an endoscopic test that allows the doctor to look inside the entire large intestine. The doctor is able to see things such as inflamed tissue, abnormal growths, ulcers and polyps. For answers to frequently asked questions about screenings, visit the American Cancer Society.
The gastroenterologist (the specialist who performs colonoscopies) will give you instructions in advance that will explain what you will need to do to prepare for your colonoscopy. MedlinePlus, a service of the U.S. National Library of Medicine and the National Institutes of Health, offers extensive information about preparing for a colonoscopy and excellent tutorials about what to expect.
About the Colon
As defined by The National Cancer Institute, “The colon and rectum are parts of the digestive system. Partly digested food enters the colon from the small intestine. The colon removes water and nutrients from the food and turns the rest into waste (stool). The waste passes from the colon into the rectum and then out of the body through the anus.”
According to the National Digestive Diseases Information Clearing House (NDDIC), “Most polyps are not dangerous. Most are benign, which means they are not cancer. But over time, some types of polyps can turn into cancer.”
Experts agree that by finding and removing polyps, a colonoscopy screening likely prevents most cancers from ever forming.
To find polyps or early colorectal cancer:
- People in their 50s and older should be screened.
- People who are at higher-than-average risk of colorectal cancer should talk with their doctor about whether to have screening tests before age 50, what tests to have, the benefits and risks of each test, and how often to schedule appointments.
The following screening tests can be used to detect polyps, cancer, or other abnormal areas. Your doctor can explain more about each test:
- Fecal occult blood test (FOBT): Sometimes cancers or polyps bleed, and the FOBT can detect tiny amounts of blood in the stool. If this test detects blood, other tests are needed to find the source of the blood. Benign conditions (such as hemorrhoids) also can cause blood in the stool.
- Sigmoidoscopy: Your doctor checks inside your rectum and the lower part of the colon with a lighted tube called a sigmoidoscope. If polyps are found, the doctor removes them. The procedure to remove polyps is called a polypectomy.
- Colonoscopy: Your doctor examines inside the rectum and entire colon using a long, lighted tube called a colonoscope. Your doctor removes polyps that may be found.
- Double-contrast barium enema: You are given an enema with a barium solution, and air is pumped into your rectum. Several x-ray pictures are taken of your colon and rectum. The barium and air help your colon and rectum show up on the pictures. Polyps or tumors may show up.
- Digital rectal exam (DRE): A rectal exam is often part of a routine physical examination. Your doctor inserts a lubricated, gloved finger into your rectum to feel for abnormal areas. According to the National Cancer Institute, www.cancer.gov, study results have shown that there is no evidence to support DRE as a screening method for colorectal cancer.
The following are two new screening tests currently being studied in clinical trials.
- Virtual colonoscopy: Virtual colonoscopy is a procedure that uses a series of x-rays called computed tomography to make a series of pictures of the colon. A computer puts the pictures together to create detailed images that may show polyps and anything else that seems unusual on the inside surface of the colon. This test is also called colonography or CT colonography. Clinical trials are comparing virtual colonoscopy with commonly used colorectal cancer screening tests. Other clinical trials are testing whether drinking a contrast that coats the stool, instead of using laxatives to clear the colon, shows polyps clearly.This method is under study. See “The Promise of Cancer Research.”
- DNA stool test: This test checks DNA in stool cells for genetic changes that may be a sign of colorectal cancer.
You may find it helpful to read the NCI fact sheet “Colorectal Cancer Screening: Questions and Answers.”
You may want to ask your doctor the following questions about screening:
- Which tests do you recommend for me? Why?
- How much do the tests cost? Will my health insurance plan help pay for screening tests?
- Are the tests painful?
- How soon after the tests will I learn the results?
Source: The Web site of the National Cancer Institute (http://www.cancer.gov)
Dedicated to Colorectal Cancer Prevention, Early Detection, and Cancer Survivorship