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Colonoscopy Questions and Answers

NEW YORK (Jun 1, 2012)

Benjamin Lebwohl, M.D.
Benjamin Lebwohl, M.D.

From Benjamin Lebwohl, M.D., a gastroenterologist at NewYork-Presbyterian/Columbia University Medical Center –

What happens the day before?

To prepare patients for a colonoscopy the gastroenterologist prescribes a set of instructions for the day before the procedure. These include dietary modification – eliminating certain solid foods and sticking to a clear liquid diet – and a purgative, a medication that cleans out the bowel. Most patients are prescribed a liquid purgative, but there are a few available in tablet form, which must be taken with a lot of water. The high volume liquid purgatives have the longest track record in terms of effectiveness, but for patients who have difficulty drinking large quantities of liquid (as much as a gallon may be required), a lower volume of liquid may be more appropriate.

While most purgatives are taken the night before the procedure, some are prescribed so that half is taken the evening before and the rest the following day closer to the time of the colonoscopy. (Several recent studies have shown that splitting the purgative in this way results in better preparation.) Whatever form they come in purgatives causes loose, frequent stools to empty the colon for the test, and you should plan to be near a bathroom.

How will doctors prep me?

Once in the procedure room, the gastroenterologist has the patient lie on his or her side, then an anesthesiologist or the gastroenterologist administers a sedative. How asleep the patient is during the procedure depends on the patient's preferences. Some prefer to be more awake and even watch the procedure on screen while others prefer to take a nap.

What happens during the procedure?

While the patient is sedated the gastroenterologist introduces a colonoscope, a flexible tube approximately five feet long and one centimeter in diameter, into the rectum and advances it to the cecum, the top of the colon. The colonoscope has a light and camera on the tip, and a channel through which other instruments can be introduced.

Once the cecum is reached, the colon is carefully inspected for polyps and cancer as the colonoscope is withdrawn. Recent studies have shown that it is important not to rush the withdrawal: physicians whose average withdrawal time is six minutes or more tend to be more accurate in identifying polyps.

Any polyps identified during the exam can usually be removed at the same time. Using a snare, a wire loop that can expand or contract and can squeeze the polyp at its base, the gastroenterologist retrieves the polyp and later sends it to a laboratory for analysis. The gastroenterologist can also biopsy any other abnormalities at this time. At the end of the procedure the colonoscope is removed.

What is the recovery like?

When patients awake they may feel like they need to pass gas because air has been introduced into the colon during the colonoscopy. Patients walk out of the endoscopy suite but may not be completely alert, so we advise them not to drive that day and to have someone accompany them home. By the next day patients are completely back to normal.

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