Colonoscopy is the visual examination of the large intestine (colon) using a lighted, flexible fiber optic video endoscope. The colon begins in the right-lower abdomen looks like a big question mark as it moves up and around the abdomen, ending in the rectum.
The colon has a number of functions including withdrawing water from the liquid stool that enters it so that a formed stool is produced. It is 5 to 6 feet long.
The flexible colonoscope is a remarkable piece of equipment that can be directed and moved around the many bends in the colon. These colonoscopes have a tiny optically sensitive computer chip at the end. Electronic signals are then transmitted up the scope to a computer, which displays the image on a large video screen. An open channel in these scopes allows other instruments to be passed through in order to perform biopsies, remove polyps or inject solutions.
Reasons for the Exam
There are many types of problems that can occur in the colon. The medical history, physical exam, laboratory tests and x-rays can provide information useful in making a diagnosis. Directly viewing the inside of the colon by colonoscopy is usually the best exam.
Colonoscopy is used for:
- Colon cancer - a serious but highly curable malignancy
- Polyps - fleshy tumors, which usually are the forerunners of colon cancer.
- Colitis (ulcerative or Crohn’s) - chronic, recurrent inflammation of the colon.
- Diverticulitis or Diverticulosis - pockets along the intestinal wall that develop over time and may become infected.
- Bleeding lesions - bleeding may occur form different points in the colon due to abnormally formed blood vessels, polyps, or divertiulitis.
- Abdominal symptoms - may include pain, discomfort particularly if associated with weight loss or anemia.
- Abnormal barium x-ray
- Chronic diarrhea, constipation or a change in bowel habits
To obtain the full benefits of the exam, the colon must be clean and free of stool. The patient receives instructions on how to do this. In involves drinking a solution, which flushes the colon clean. Usually the patient eats no food after noon the day before the test and drinks clear liquids up until two hours before the test. Regular medications should be discussed with your doctor at least a week before the procedure.
Colonoscopy is usually performed on an outpatient basis. The patient is mildly sedated; the endoscope is inserted through the anus and moved gently around the bends of the colon. If a polyp is encountered, a thin wire snare is used to lasso it. Electrocautery (electrical heat) is applied to painlessly remove it. Other tests can be performed during colonoscopy, including biopsy to obtain a small tissue specimen for microscopic analysis.
The procedure takes 15 to 30 minutes and is seldom remembered by the sedated patient. The patient is then transported to the recovery area to monitor vital signs until the patient is fully awake. It is normal to experience mild cramping, abdominal pressure, or large amounts of flatus following the exam. This usually subsides within an hour or so.
After the exam, the physician explains the findings to the patient and family. If the effects of the sedatives are prolonged, the physician may suggest an appointment at a later date. If a biopsy has been performed or a polyp removed, the results are not available for 3 to 7 days.
A colonoscopy is performed to identify and/or correct a problem in the colon. The test enables a diagnosis to be made and specific treatment can be given. If a polyp is found during the exam it can be removed at that time eliminating the need for a major operation later. If a bleeding site is identified, treatment may be administered to stop the bleeding. Other treatments may be given through the endoscope when necessary.
Alternative tests to colonoscopy include a barium enema, virtual colonoscopy or other types of x-ray exams that outline the colon and allow a diagnosis to be made. Study of the stools and blood can provide indirect information about a colon condition. These exams, however, do not allow direct viewing of the colon, removal of polyps or the completion of biopsies.
Side Effects and Risks
Bloating and distention typically occur for about an hour after the exam until the air is expelled. Serious risks with colonoscopy, however, are very uncommon. One such risk is excessive bleeding, especially with the removal of a large polyp. In rare instances, a tear in the lining of the colon can occur. These complications may require hospitalization and rarely surgery.
Due to the mild sedation, the patient should not drive or operate machinery following the exam. For this reason, this facility will not perform a sedated procedure on a person with no ride home!