Colonoscopy

Colonoscopy is a procedure that enables an examiner (usually a gastroenterologist) to evaluate the appearance of the inside of the colon (large bowel). This is accomplished by inserting a flexible tube that is about the thickness of a finger into the anus, and then advancing it slowly, under visual control, into the rectum and through the colon. It is performed with the visual control of either looking through the instrument or with viewing a TV monitor.

Why is colonoscopy done?

This test may be done for a variety of reasons. Most often it is done to investigate the finding of blood in the stool, abdominal pain, diarrhea, a change in the bowel habits, or an abnormality found on colon x- ray or a CT scan. Certain individuals with previous history of polyps or colon cancer and certain individuals with family history of particular malignancies or colon problems may be advised to have periodic colonoscopies because they are at a greater risk of polyps or colon cancer.

What bowel preparation is needed for colonoscopy?

If the procedure is to be complete and accurate, the colon must be completely clean. Patients are given detailed instructions about the cleansing of the colon procedure. In general this consists of a large volume of a special cleansing solution or several days of a clear liquid diet and laxatives or enemas prior to the examination. These instructions should be followed to the letter or the procedure may be unsatisfactory and have to be repeated later or a less accurate alternative chosen in its place.

What about current medications or diet before colonoscopy?

Most medications should be continued as usual, but some may interfere with the examination. It is best that the physician is informed of all current prescription or over the counter medications. Aspirin products, blood thinners (Coumadin, etc.), arthritis medications, insulin, and iron preparations are examples of medications that may require special instructions. The physician will also want to be aware of the patient's allergies and any other major illnesses. The examiner should be alerted if, in the past, patients have required antibiotics prior to surgical or dental procedures. Instructions may also be given to avoid certain foods for a couple of days prior to the procedure, such as stringy foods, foods with seeds, or red Jello.

What to expect during colonoscopy?

Prior to the procedure an IV is started and the patient is given a monitor for continuous monitoring of the heart, blood pressure, and oxygenation of the blood. Medication is often given through the vein to make the patient sleepy and relaxed. If needed, the patient may receive additional doses during the procedure. Colonoscopy often gives a feeling of pressure, cramping, and bloating, however, with the aid of the medication it is generally well tolerated and rarely causes any significant pain.

Patients will be lying on their left side or back as the instrument is slowly advanced. Once the tip of the colon, or the last portion of the small bowel, is reached the colonoscope is slowly withdrawn and the lining is again carefully examined. The procedure usually takes 15 to 60 minutes. If the entire colon, for some reason, can not be visualized, the physician may decide to try it at a later date with a better bowel preparation or may decide to order an x-ray of the colon.