Virtual Colonoscopy
National Digestive Diseases Information Clearinghouse
What is virtual colonoscopy? that make up the GI tract are the mouth, esophagus, stomach, small intestine, large Virtual colonoscopy, also called intestine—which includes the appendix, computerized tomography (CT) cecum, colon, and rectum—and anus. The colonography, is a procedure that uses intestines are sometimes called the bowel. a combination of x rays and computer The last part of the GI tract—called the technology to create images of the rectum lower GI tract—consists of the large intestine and entire colon. Virtual colonoscopy can and anus. show irritated and swollen tissue, ulcers, and polyps—extra pieces of tissue that grow on the lining of the intestine. This procedure is different from colonoscopy, which uses a long, flexible, Esophagus narrow tube with a light and tiny camera Mouth on one end, called a colonoscope or scope, to look inside the rectum and entire colon. Read more in Colonoscopy at Stomach www.digestive.niddk.nih.gov.
What are the rectum and colon? The rectum and colon are part of the gastrointestinal (GI) tract, a series of hollow Small organs joined in a long, twisting tube from intestine the mouth to the anus, a 1-inch-long opening through which stool leaves the body. The Large body digests food using the movement intestine of muscles in the GI tract, along with the Appendix release of hormones and enzymes. Organs Rectum Anus
The GI tract The large intestine is about 5 feet long in enough evidence exists to fully assess its adults and absorbs water and any remaining effectiveness as a screening tool. Instead, nutrients from partially digested food passed the U.S. Preventive Services Task Force from the small intestine. The large intestine recommends fecal occult blood testing, then changes waste from liquid to a solid sigmoidoscopy, or colonoscopy for colon matter called stool. Stool passes from the cancer screening.1 colon to the rectum. The rectum is 6 to The American College of Gastroenterology 8 inches long in adults and is located between recommends screening for colon cancer2 the last part of the colon—called the sigmoid colon—and the anus. The rectum stores • at age 50 for people who are not at stool prior to a bowel movement. During increased risk of the disease a bowel movement, stool moves from the • at age 45 for African Americans rectum to the anus. because they have an increased risk of developing the disease Why is a virtual colonoscopy A gastroenterologist may recommend performed? earlier screening for people with a family A virtual colonoscopy is performed to help history of colon cancer, a personal history of diagnose inflammatory bowel disease—a long-lasting disorder that causes irritation and sores in • changes in bowel habits the GI tract—or other risk factors for colon • abdominal pain cancer. • bleeding from the anus Medicare and private insurance companies • weight loss sometimes change whether and how often they pay for cancer screening tests. People A gastroenterologist—a doctor who should check with their insurance company specializes in digestive diseases—may also to find out how often they can get a screening order a virtual colonoscopy as a screening virtual colonoscopy that their insurance will test for colon cancer. Screening is testing cover. for diseases when people have no symptoms. Screening may find a disease at an early Read more about colon cancer at stage, when a gastroenterologist has a better www.cancer.gov. chance of curing the disease. However, while some gastroenterologists use a virtual colonoscopy to screen for colon cancer, not
1U.S. Preventive Services Task Force. Screening for Colorectal Cancer: U.S. Preventive Services Task Force Recommendation Statement. Rockville, MD: Agency for Healthcare Research and Quality; 2008. AHRQ Publication 08–05124–EF–3. Report. 2Rex DK, Johnson DA, Anderson JC, Schoenfeld PS, Burke CA, Inadomi JM. American College of Gastroenterology guidelines for colorectal cancer screening 2008. American Journal of Gastroenterology. 2009;104(3):739–750. 2 Virtual Colonoscopy How does a person prepare include following a clear liquid diet for 1 to 3 days before the procedure for a virtual colonoscopy? and avoiding drinks that contain red Preparation for a virtual colonoscopy or purple dye. The instructions will includes the following steps: provide specific direction about when • Talk with a gastroenterologist. to start and stop the clear liquid diet. When people schedule a virtual People may drink or eat the following: colonoscopy, they should talk with – fat-free bouillon or broth their gastroenterologist about medical – strained fruit juice, such as apple conditions they have and all prescribed or white grape—orange juice is not and over-the-counter medications, recommended vitamins, and supplements they take, – water including – plain coffee or tea, without cream or – aspirin or medications that contain milk aspirin – sports drinks in flavors such as – nonsteroidal anti-inflammatory drugs lemon, lime, or orange such as ibuprofen or naproxen – gelatin in flavors such as lemon, lime, – arthritis medications or orange – blood thinners The person needs to take laxatives – diabetes medications and enemas the night before a virtual – vitamins that contain iron or iron colonoscopy. A laxative is medication supplements that loosens stool and increases bowel Women should let their gastroenterologist movements. An enema involves know if they are pregnant. Developing flushing water or laxative into the fetuses are particularly sensitive to rectum using a special wash bottle. x rays. The x-ray technician should Laxatives and enemas can cause take special precautions to minimize diarrhea, so the person should stay close exposure, or the gastroenterologist may to a bathroom during the bowel prep. suggest an alternative procedure, such Laxatives are usually swallowed in pill as a colonoscopy. form or as a powder dissolved in water. • Cleanse the bowel. The gastroenterologist Some people will need to drink a large will give written bowel prep instructions amount, usually a gallon, of liquid to follow at home. A gastroenterologist laxative at scheduled times. People orders a bowel prep so that little to may find this part of the bowel prep no stool is present inside the person’s difficult; however, it is very important to intestine. A complete bowel prep complete the prep. The images will not lets the person pass stool that is clear. be clear if the prep is incomplete. Stool inside the colon can prevent the People should call the gastroenterologist CT scanner from taking clear images of if they are having side effects that are the intestinal lining. Instructions may preventing them from finishing the prep.
3 Virtual Colonoscopy • Drink contrast medium. The night abnormalities, a gastroenterologist may before the procedure, the person will perform a colonoscopy the same day or at a drink a liquid that contains a special later time. dye, called contrast medium. Contrast medium is visible on x rays and can help distinguish between stool and polyps. Seek Help for Emergency How is a virtual colonoscopy Symptoms performed? People who have any of the following A radiologist—a doctor who specializes symptoms after a virtual colonoscopy in medical imaging—performs a virtual should seek immediate medical colonoscopy at an outpatient center or a attention: hospital. A person does not need anesthesia. • severe abdominal pain For the test, the person will lie on a table • fever while the radiologist inserts a thin tube through the anus and into the rectum. The • bloody bowel movements or tube inflates the large intestine with air for bleeding from the anus a better view. The table slides into a tunnel- • dizziness shaped device where the radiologist takes the • weakness x ray images. The radiologist may ask the person to hold his or her breath several times during the test to steady the images. The radiologist will ask the person to turn over on the side or stomach so the radiologist can What are the risks of virtual take different images of the large intestine. colonoscopy? The procedure lasts about 10 to 15 minutes. The risks of virtual colonoscopy include • exposure to radiation What can a person expect • perforation—a hole or tear in the lining after a virtual colonoscopy? of the colon After a virtual colonoscopy, a person can expect Radiation exposure can cause cancer. However, though the level of radiation • cramping or bloating during the first exposure that leads to cancer is unknown, hour after the test the risk from these types of tests is thought • to resume regular activities immediately to be small. Inflating the colon with air has a after the test small risk of perforating the intestinal lining. Perforation may need to be treated with • to return to a normal diet surgery. After the test, a radiologist interprets the Virtual colonoscopy shows the entire images, evaluates the results to find any abdomen—the area between the chest abnormalities, and sends a report to the and the hips—and can show abnormalities gastroenterologist. If the radiologist finds outside of the GI tract. These findings may lead to additional testing, cost, and anxiety.
4 Virtual Colonoscopy Work with a Gastroenterologist • If a virtual colonoscopy shows a to Determine the Best polyp or cancer, a colonoscopy may be needed to confirm or treat the Screening Method abnormality; with a colonoscopy, Virtual colonoscopy has several advantages treatment can occur at the same time and disadvantages when compared with as diagnosis. a colonoscopy. The advantages of virtual
colonoscopy include the following: • Virtual colonoscopy may not be as effective as colonoscopy at detecting • Virtual colonoscopy does not require certain polyps. the insertion of a colonoscope into the • Virtual colonoscopy may entire length of the colon. interfere with personal medical • People do not need anesthesia. devices. People should tell the People can return to their normal gastroenterologist about any activities or go home after the implanted medical devices. procedure without the help of another • Medicare and private insurance person. companies sometimes change • Virtual colonoscopy takes less time whether and how often they pay for than colonoscopy. cancer screening tests. People should • The radiologist can use a virtual check with their insurance company colonoscopy to view the inside of a to find out how often they can get a colon that is narrowed because of screening virtual colonoscopy that inflammation or the presence of a their insurance will cover. polyp. • Virtual colonoscopy is a newer technology and not all medical The disadvantages of virtual colonoscopy facilities make this procedure include the following: available. • People require bowel prep and the • Gastroenterologists do not insertion of a tube into the rectum. recommend techniques that use • The radiologist cannot remove tissue x-ray radiation for pregnant women samples or polyps or stop bleeding if a because the radiation may harm the perforation occurs. fetus.
5 Virtual Colonoscopy Points to Remember • The gastroenterologist will give written bowel prep instructions to • Virtual colonoscopy, also called follow at home. A gastroenterologist computerized tomography (CT) orders a bowel prep so that little to colonography, is a procedure that uses no stool is present inside the person’s a combination of x rays and computer intestine. technology to create images of the rectum and entire colon. • The images will not be clear if the prep is incomplete. • Virtual colonoscopy can show irritated and swollen tissue, ulcers, and • The night before the procedure, polyps—extra pieces of tissue that the person will drink a liquid that grow on the lining of the intestine. contains a special dye, called contrast medium. A radiologist—a doctor • A virtual colonoscopy is performed to who specializes in medical imaging— help diagnose performs a virtual colonoscopy at an – changes in bowel habits outpatient center or a hospital. For – abdominal pain the test, the person will lie on a table – bleeding from the anus while the radiologist inserts a thin tube through the anus and into the rectum. – weight loss The tube inflates the large intestine • A gastroenterologist may also order a with air for a better view. The table virtual colonoscopy as a screening test slides into a tunnel-shaped device for colon cancer. where the radiologist takes the x-ray images. • Preparation for a virtual colonoscopy includes talking with • The risks of virtual colonoscopy a gastroenterologist about medical include exposure to radiation and conditions the person has and perforation—a hole or tear in the medications the person is taking, as lining of the colon. well as cleansing the bowel.
6 Virtual Colonoscopy Hope through Research American College of Gastroenterology 6400 Goldsboro Road, Suite 200 The National Institute of Diabetes and Bethesda, MD 20817–5846 Digestive and Kidney Diseases (NIDDK) Phone: 301–263–9000 conducts and supports basic and clinical Fax: 301–263–9025 research into many digestive disorders. Email: [email protected] Clinical trials are research studies involving Internet: www.gi.org people. Clinical trials look at safe and American Gastroenterological Association effective new ways to prevent, detect, or 4930 Del Ray Avenue treat disease. Researchers also use clinical Bethesda, MD 20814 trials to look at other aspects of care, such Phone: 301–654–2055 as improving the quality of life for people Fax: 301–654–5920 with chronic illnesses. To learn more about Email: [email protected] clinical trials, why they matter, and how to Internet: www.gastro.org participate, visit the NIH Clinical Research Trials and You website at www.nih.gov/health/ International Foundation for Functional clinicaltrials. For information about current Gastrointestinal Disorders studies, visit www.ClinicalTrials.gov. 700 West Virginia Street, Suite 201 Milwaukee, WI 53204 For More Information Phone: 1–888–964–2001 or 414–964–1799 Fax: 414–964–7176 Read more about other diagnostic Email: [email protected] tests in these publications at Internet: www.iffgd.org www.digestive.niddk.nih.gov: National Cancer Institute • Colonoscopy BG 9609 MSC 9760 • ERCP (Endoscopic Retrograde 9609 Medical Center Drive Cholangiopancreatography) Bethesda, MD 20892 Phone: 1–800–4–CANCER (1–800–422–6237) • Flexible Sigmoidoscopy Internet: www.cancer.gov • Liver Biopsy • Lower GI Series • Upper GI Endoscopy • Upper GI Series
7 Virtual Colonoscopy Acknowledgments National Digestive Diseases Publications produced by the Clearinghouse Information Clearinghouse are carefully reviewed by both NIDDK 2 Information Way scientists and outside experts. This Bethesda, MD 20892–3570 publication was originally reviewed by Phone: 1–800–891–5389 Michael Wallace, M.D., Mayo Clinic. TTY: 1–866–569–1162 Fax: 703–738–4929 Email: [email protected] You may also find additional information about this Internet: www.digestive.niddk.nih.gov topic by visiting MedlinePlus at www.medlineplus.gov. This publication may contain information about The National Digestive Diseases Information medications and, when taken as prescribed, Clearinghouse (NDDIC) is a service of the the conditions they treat. When prepared, this publication included the most current information National Institute of Diabetes and Digestive available. For updates or for questions about and Kidney Diseases (NIDDK). The any medications, contact the U.S. Food and Drug NIDDK is part of the National Institutes of Administration toll-free at 1–888–INFO–FDA (1–888–463–6332) or visit www.fda.gov. Consult your Health of the U.S. Department of Health health care provider for more information. and Human Services. Established in 1980, the Clearinghouse provides information about digestive diseases to people with digestive disorders and to their families, health care professionals, and the public. The NDDIC answers inquiries, develops and distributes publications, and works closely with professional and patient organizations and Government agencies to coordinate resources about digestive diseases.
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NIH Publication No. 13–5095 September 2013
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