• Medical Author:
    Jay W. Marks, MD

    Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

  • Medical Editor: Bhupinder S. Anand, MBBS, MD, DPHIL (OXON)
    Bhupinder S. Anand, MBBS, MD, DPHIL (OXON)

    Bhupinder S. Anand, MBBS, MD, DPHIL (OXON)

    Dr. Anand received MBBS degree from Medical College Amritsar, University of Punjab. He completed his Internal Medicine residency at the Postgraduate Institute of medical Education and Research, Chandigarh, India. He was trained in the field of Gastroenterology and obtained the DPhil degree. Dr. Anand is board-certified in Internal Medicine and Gastroenterology.

Quick GuideDigestive Disorders: Common Misconceptions

Digestive Disorders: Common Misconceptions

What's new in colonoscopy? (Continued)

Chromoendoscopy uses dyes (stains) that are sprayed on the colon lining to differentiate normal lining from neoplastic (benign, premalignant, and malignant) tissues and determine which lesions should be removed or biopsied.

Fluorescence endoscopy uses fluorescein-labelled chemicals either sprayed on the lining of the colon or injected intravenously. The chemicals are taken up by abnormal cells (premalignant and malignant) of the colon's lining more than the normal cells, and special lighting make the areas of abnormal cells clearer to see so they can be biopsied or removed completely. Confocal laser endoscopy uses a particular wavelength of light that penetrates the lining of the fluorescein-stained colon for several millimeters. Abnormal cells may be more clearly identified than with fluorescein staining alone.

There are even colonoscopes and accessories that allow a retrograde view of the colon in addition to the antegrade view from the tip of the colonoscope. Thus, images are obtained in two, 180 degree-opposed directions in order to identify lesions that might be hiding behind folds in the lining of the colon that would be missed by a standard, forward-viewing colonoscope. There are even attempts to develop a self-advancing colonoscope.

Most of these newer colonoscopic techniques, with the exception of high resolution imaging, are still considered experimental. Which one(s) will ultimately turn out to be valuable adjuncts to colonoscopy has yet to be determined.

Finally, magnetic resonance imaging (MRI) can be used to examine the colon in a manner similar to CT virtual colonoscopy. The major advantage of MRI is that there is no radiation exposure; otherwise, the limitations are similar to CT virtual colonoscopy.

Reviewed on 10/11/2016
Medically reviewed by John A. Daller, MD; American Board of Surgery with subspecialty certification in surgical critical care


UpToDate. Patient information: Colonoscopy (Beyond the Basics). IMAGES:


2.Getty Images/Visuals Unlimited, Inc./Carol & Mike Werner




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