New endoscopic device improves detection of polyps in colon
2 June 2008
A multi-institutional study has shown that a new device, the third
eye retroscope developed by Avantis Medical Systems, improves the
ability of physicians to visualize abnormalities in the colon.
The study shows that when used in combination with a standard
colonoscope, the device detects a significantly higher number of
adenomas and other polyps than the colonoscope alone. It has been
cleared for use in the US by the Food and Drug Administration (FDA).
Avantis says that the third eye retroscope is designed to complement,
not to replace, standard colonoscopes. Therefore it does not alter
existing procedural infrastructure or referral patterns. The device can
be used with most of the adult colonoscopes currently produced by the
leading manufacturers, as well as some paediatric colonoscopes.
Colorectal cancer is the second greatest cause of cancer death in the
US. However, most cancers of the lower gastrointestinal (GI) tract can
be completely cured if they are detected early. Even more cases can be
completely prevented if pre-cancerous polyps can be removed before they
Principal Investigator Dr Waye, of Mount Sinai Hospital in New York,
presented the study at the Digestive Disease Week conference in San
Diego on 21 May. The multi-centre study has evaluated 214 patients to
date at eight sites across the US. During the study, patients were
examined using the retroscope in combination with a standard colonoscope.
"Colonoscopy is currently considered the best method for colorectal
cancer screening. However, it is well-established from previous research
that lesions may be missed, especially on the proximal aspect of
haustral folds and flexures or behind the ileocecal valve," said Dr.
Used during colonoscopy, the retroscope is an auxiliary imaging
device that provides retrograde illumination and visualisation of the
colon for diagnostic purposes. The device is passed through the
instrument channel of a standard colonoscope until it extends beyond the
tip of the colonoscope. As it emerges, the device automatically turns
around 180 degrees to provide a continuous retrograde view while the
colonoscope is being withdrawn.
Colonoscopy is widely regarded as the 'gold standard' for detection
of abnormalities in the colon. However, previous research has revealed
that 12-24% of polyps and a significant number of cancers can be missed
during colonoscopy, especially if they lie behind folds in the colon
wall [1, 2, 3]. This new device is designed to solve this problem by
allowing the physician to view the opposite side of those folds during
The study (which is still active) has found that, in combination with
a standard colonoscope, the device detected 13.3% additional polyps, and
12.4% additional adenomas, compared with the colonoscope alone. Polyps
detected with the device were comparable in size to those seen with the
"Our investigators are finding that the third eye retroscope is a
promising new technology for improving visualization during
colonoscopy," continued Dr Waye. "During the study, the Third Eye
revealed areas that are often hidden from the forward-viewing
colonoscope, and it allowed a significant increase in detection of
adenomas and other polyps."
In the 214 patients studied to date, 203 polyps were identified with
the standard colonoscope. With the new device, an additional 27 polyps
were detected, an increase of 13.3%. With the standard colonoscope, 105
adenomas were found; and with the retroscope, an additional 13 adenomas
were detected, an increase of 12.4%. Mean size for polyps found by the
colonoscope alone was 0.49 cm, and mean size for polyps found by the
retroscope was virtually identical, at 0.47 cm.
In 21 patients (9.8%), at least one additional polyp was found with
the use of the retroscope, and in seven patients (3.3%), the polyp
detected with the retroscope was the only one found.