Colonoscopy represents a major advance for diagnosis and treatment of diseases of the colon and rectum. Colonoscopy enables the physician to visualize disease processes which cannot normally be diagnosed with certainty or which do not show on standard x-rays, lower GI series, or barium enemas. Frequently, this examination is done to locate and treat colon and rectal polyps (small benign or malignant growths of the large intestine). The examination is performed using a colonoscope , a long, flexible tube that permits the examiner to visualize the inside of the colon (large intestine).
The ability to remove polyps through the colonoscope in the outpatient setting provides the patient with a relatively safe technique that avoids major surgery and costly hospitalization. Following colonoscopic polypectomy, patients can usually return to their normal activities within 24 hours. Colonoscopy is also frequently used as part of a diagnostic workup for rectal bleeding or inflammatory bowel disease . Finally, it is used as a surveillance technique in patients who have undergone removal of parts of their intestine for cancerous growths. Periodic examination permits early diagnosis of recurrent cancer and/or removal of pre-cancerous polyps before they become malignant.
Proper preparation for colonoscopic examination is extremely important. The large intestine must be clean and empty for an adequate examination. Preparation for colonoscopy can be accomplished the day prior to the examination. Colonoscopy is performed in the Outpatient Department of Scripps Memorial Hospital or the La Jolla Endoscopy Center (Suite 980) in the Scripps Ximed Medical Building. An IV is started in order to administer medications. In order to reduce apprehension and discomfort during the examination, Fentanyl (a narcotic) and Versed (a sedative) are usually given intravenously at the beginning of the examination. These will cause sedation and may cause some light-headedness.
Colonoscopy is performed on a comfortable examining table with the patient lying on the left side. A lubricant is applied around the anal opening and the instrument is inserted into the rectum. The scope is then manipulated so that the entire lining of the large intestine can be seen. In order to do this, the examiner must instill small amounts of air into the colon. This can cause a sensation of distention and fullness. The large intestine (colon) can be very redundant and can contain many turns and folds. As the scope passes around some of these turns, one may experience a cramping or tugging sensation. This sensation is usually relieved as the instrument and the colon are straightened.
Colonoscopy usually takes 15 to 60 minutes. If polyps are present and removed, the length of the procedure will be longer. A nurse is always present to help the examiner and to monitor the patient during the examination. When the procedure is completed, patients are observed for a period of time in a recovery area until the effects of the medications have subsided .
When polyps are found, they are removed by placing a wire loop about the base of the polyp. An electrical current is applied to the wire loop in order to cut the polyp off at its base. Since the intestine has no pain fibers patients d not experience any discomfort or pain during removal. The polyp is then retrieved by applying suction to the colonoscope and catching the polyp on the tip of the instrument. Both the polyp and the instrument are then withdrawn. The polyp is sent to the laboratory for microscopic evaluation. If more than one polyp is present, it may be necessary to re-insert the colonoscope in order to remove them.
All medical procedures carry inherent risks. With a colonoscopy, the most serious risk is perforation of the bowel. This may occur when a polyp is removed or, occasionally, with other manipulation. Fortunately, this is rare. Other uncommon risks are bleeding and medication reaction.