Colonoscopy is a medical procedure during which a long, flexible, tubular instrument called the colonoscope is used to view the entire inner lining of the colon (large intestine) and the rectum.
A colonoscopy is generally recommended when the patient complains of rectal bleeding or has a change in bowel habits or other unexplained abdominal symptoms. The test is frequently used to test for colorectal cancer, especially when polyps or tumor-like growths have been detected using the barium enema and other diagnostic tests. Polyps can be removed through the colonoscope and samples of tissue (biopsies) can be taken to test for the presence of cancerous cells.
The test also enables the physician to check for bowel diseases such as ulcerative colitis and Crohn's disease. It is a necessary tool in monitoring patients who have a past history of polyps or colon cancer. It may also be used as a screening tool for people at high risk of developing colon cancer, such as those with a strong family history of the disease.
Patients who are pregnant or have a history of heart and lung disease and those with blood-clotting problems should tell the doctor about their health history before the procedure. Special precautions may be needed. For instance, a patient with artificial heart valves or a history of infection of the lining of the heart may need to take antibiotics to prevent infection. Patients also should tell the doctor about all medications they are taking. The doctor may want the patient to stop taking some drugs, such as aspirin, for a period of time before the procedure. Patients with some intestinal conditions should not have a colonoscopy. Examples of these conditions include acute diverticulitis, acute inflamatory bowel disease, a suspected perforation or break in the intestines, and recent abdominal surgery. Patients must be able to cooperate during the procedure.
The procedure can be done either in the doctor's office or in a special procedure room of a local hospital. An intravenous (IV) line will be started in a vein in the arm. Through the IV line, the patient generally receives a sedative and a pain-killer if needed.
During the colonoscopy, the patient will be asked to lie on his/her left side with his/her knees drawn up toward the abdomen. The doctor begins the procedure by inserting a lubricated, gloved finger into the anus to check for any abnormal masses or blockage. A thin, well-lubricated colonoscope will then be inserted into the anus and it will be gently advanced through the colon. The lining of the intestine will be examined through the scope. Air is pumped through the colonoscope to help clear the path or make it easier to view the lining of the colon. If there are excessive secretions, stool or blood that obstruct the viewing, they will be suctioned out through the scope. The doctor may press on the abdomen or ask the patient to change his/her position in order to advance the scope through the colon.
The entire length of the large intestine can be examined in this manner. If suspicious growths are observed, tiny biopsy forceps or brushes can be inserted through the colonoscope and tissue samples can be obtained. Small polyps can also be removed through the colono-scope. Biopsies and the removal of polyps through the colonoscope are both painless procedures. After the procedure, the colonoscope is slowly withdrawn and the instilled air is allowed to escape. The anal area is then cleansed with tissues.
The procedure may take anywhere from 30 minutes to one hour, depending on how easy it is to advance the scope through the colon.
The bowel cleaning preparation may be tiring and often produces diarrhea and cramping. During the colonoscopy, the sedative will keep the patient drowsy and relaxed. Most patients complain of minor discomfort, such as cramping or a feeling of fullness. However, the procedure is not painful.
The doctor should be notified if the patient has allergies to any medications or anesthetics, has any bleeding problems, or if a female patient is pregnant. The doctor should also be informed of all the medications that the patient is currently taking and if he or she has had a barium x-ray examination recently. The doctor may instruct the patient not to take certain medications, like aspirin
It is important that the colon be thoroughly cleaned before performing the examination. Hence, before the examination, considerable preparation is necessary to clear the colon of all stool. The patient will be asked to refrain from eating any solid food for 24-48 hours before the test. Only clear liquids such as juices, broth, and gelatin are recommended. The patient is advised to drink plenty of water to avoid dehydration.
The day before the test, the patient will have to drink a special cleansing solution or take a strong laxative that the doctor has prescribed. The patient will also be given specific instructions as to how to use an enema, as a warm water enema may be necessary the next morning.
On the morning of the examination, one or two enemas of warm tap water may have to be taken. Generally, the procedure has to be repeated until the return from the enema is clear of stool particles. The patient is instructed not to eat or drink anything. The preparatory procedures are extremely important because the colon must be thoroughly clean for the exam to be performed.
After the procedure, the patient is kept under observation until the effects of the medications wear off. The patient will not be able to drive immediately after the procedure and can generally resume a normal diet and usual activities unless otherwise instructed. The patient will be advised to drink lots of fluids to replace those lost by laxatives and fasting.
For a few hours after the procedure, the patient may feel groggy. There may be some abdominal cramping and a considerable amount of gas may be passed. If a biopsy was performed or a polyp was removed, there may be small amounts of blood in the stool for a few days. If the patient experiences severe abdominal pain or has persistent and heavy bleeding, it should be brought to the doctor's attention immediately.
The procedure is considered safe. Very rarely (2 in 1, 000 cases) there may be a perforation (a hole) in the intestinal wall. Heavy bleeding due to the removal of the polyp or from the biopsy site occurs very infrequently (1 in 1, 000 cases). Infections due to a colonoscopy are also extremely rare. Patients with artificial or abnormal heart valves are usually given antibiotics before and after the procedure to prevent an infection.
The results are said to be normal if the lining of the colon is a pale reddish pink and there are no abnormal looking masses that are found in the lining of the colon.
Abnormal results would imply that polyps or other suspicious-looking masses were detected in the lining of the intestine. Polyps can be removed during the procedure
Abnormal findings also could be due to inflammatory bowel diseases such as ulcerative colitis or Crohn's disease. A condition called diverticulosis, in which many small fingerlike pouches protrude from the colon wall, may also be identified.
Berkow, Robert et al., eds. Merck Manual of Diagnosis and Therapy, 17th edition. Rahway, NJ: Merck Publishing Group, 1999.
Fauci, Anthony S. "Gastrointestinal Endoscopy." In Harrison's Principles of Internal Medicine, 14th edition. New York, NY: The McGraw-Hill Companies, 2000.
Pfenninger, John L. Procedures for Primary Care Physicians, 2nd edition. St. Louis: Mosby, Inc. 2000.
Stauffer, Joseph and Joseph C. Segen. The Patient's Guide to Medical Tests. New York: Facts On File, 1997.
American Cancer Society (National Headquarters). 1599Clifton Road, N.E. Atlanta, Georgia 30329. (800) 227-2345. <http://www.cancer.org>
American Gastroenterological Association. 7910 Woodmont Ave., Seventh Floor, Bethesda, MD 20814. Phone: (301) 654-2055. www.gastro.org.
Cancer Research Institute (National Headquarters). 681 Fifth Avenue, New York, N.Y. 10022. (800) 992-2623. <http://www.cancerresearch.org>
National Cancer Institute. 9000 Rockville Pike, Building 31, Room 10A31, Bethesda, Maryland, 20892. (800) 422-6237. <http://www.icic.nci.nih.gov>
Society of American Gastrointestinal Endoscopic Surgeons (SAGES). 2716 Ocean Park Boulevard, Suite 3000, Santa Monica, CA 90405. (310) 314-2404. <http://www.sages.org>
United Ostomy Association, Inc. (UOA). 19772 MacArthur Blvd., Suite 200, Irvine, CA 92612. (800) 826 0826. <http://www.uoa.org.>
Lata Cherath, Ph.D.
—Removal of a tissue sample for examination under the microscope to check for cancer cells.
—A thin, flexible, hollow, lighted tube that in inserted through the rectum into the colon to enable the doctor to view the entire lining of the colon.
—A chronic inflammatory disease resulting from the immune system attacking one's own body. The disease generally affects the gastrointestinal tract and may cause the formation of deep ulcers.
—A pouchlike section that bulges through the large intestine's muscular walls but is not inflamed. It may cause bleeding, stomach distress and excess gas.
—A doctor who specializes in the diagnosis of disease by studying cells and tissues under a microscope.
—An abnormal growth that develops on the inside of a hollow organ such as the colon.
QUESTIONS TO ASK THE DOCTOR
- Did you see any abnormalities?
- How soon will you know the results of the biopsy (if one was done)?
- When can I resume any medications that were stopped?
- What future care will I need?