A colonoscopy procedure uses a colonoscope–a long flexible tube about the size of a finger. It is inserted into the rectum and passed into the entire length of the colon to the cecum, the beginning of the colon found on the right side of the abdomen, and where the terminal ileum or end of the small bowel enters. By this means, abnormalities seen by x-ray or suspected at the time of the history and physical exam can be investigated and studied in detail. Abnormalities which may be too small to be seen by x-ray can also be identified. When abnormalities are seen by this endoscopic procedure they can be biopsied.
Polyps can be removed through the colonoscope. The colonoscope has a built in video chip at its tip from which an image of the colon is transmitted through the instrument to a processor adjacent to the patient who is lying on a cart. This image is then projected to a video monitor across from the physician. As the physician performs the procedure, he watches the video monitor as it transmits the image from the colon lumen. Although there is some discomfort associated with a colonoscopy it is minimized by giving the patient analgesic agents intravenously prior to and during the procedure.
During the procedure the patient is monitored for blood pressure, pulse and oxygen level. The patient normally lies on their left side but the position may be changed so to a supine position or a right side position. The patient may fall asleep during the procedure and some of the medications given to the patient will give an amnestic effect, in which case they will not be able to remember the procedure itself. Medications will be administered through an intravenous line placed prior to the procedure.
During the examination, a polyp may be found. This is a growth oftentimes no larger than the tip of a finger, which is often premalignant. If appropriate, the polyp may be removed through the instrument, either by biopsy or by snare with electrocautery. No pain is felt during removal of these polyps. Although a majority of polyps are noncancerous, some may have areas of malignancy in them and may even be invasive in nature. Therefore, a polypectomy is a very important procedure performed by the gastroenterologist.
On the day prior to the procedure and on the day of the procedure, the patient is required to take medication to cleanse the bowel. There are many types of cleansing protocols. The colon must be completely empty of waste, so only liquids should be taken on the day prior to the examination. Detailed instructions must be followed very carefully so that the physician is able to see the entire colon lining. If there is residual stool present, the physician may not be able to remove polyps safely and may ask the patient to return for a repeat of the examination.
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Following the procedure, the patient may feel somewhat drowsy, and will be observed the next 30–60 minutes. The patient should not drive home because of the sedation given, and for this reason must arrange transportation home following the procedure. Because of the sedative effects of the medication it is suggested that the patient not return to work the day of the procedure nor try to perform any fine detail work, cooking, check writing, or driving.
Colonoscopy and polypectomy are quite safe with the incidence of perforation or bleeding of the colon less than 1 per 1000 patients. If a perforation or tear in the lining of the bowel occurs oftentimes this will not occur immediately but will occur within the next 24–48 hours. Patients will be aware of severe abdominal pain, loss of appetite, and severe abdominal cramps. Often a colon perforation can be managed without surgery with antibiotic and intravenous fluids. Sometimes surgery may be required.
Another complication of polypectomy and biopsy is bleeding. This is usually minor and stops by itself, but may require repeat colonoscopy and cauterization. Rarely are transfusions or surgery needed.
A third complication may be related to the intravenous use of sedation. Localized phlebitis or irritation of the vein may occur with certain medications. A tender lump appears at the site of the IV. Other drug reactions may also occur.
Colonoscopy is a diagnostic test of the large bowel that has greater sensitivity and specificity than x-rays or virtual colonoscopy, another radiographic study of the colon. Even when x-rays are negative, causes of rectal bleeding or evidence of colitis may be seen with the colonoscopy examination. Periodic colonoscopy is useful in patients who have had polyps or cancer in the past, especially if they have a family history of colon cancer. It is a safe examination which may take less than 20 minutes to perform and has a very high safety profile.
Rush University Medical Center
1725 W Harrison St, Room 837
Chicago, IL 60612
Advocate Illinois Masonic
3000 N Halsted St, Suite 609
Chicago, IL 60657
Mon, Tue, Thu: 7 AM - 5 PM
Dr. Markey Direct
William Markey, MD
Gastroenterology & Internal Medicine