LOS ANGELES — New methods and devices for diagnostic colonoscopy improve the physician's ability to image the entire colon and to identify so-called hidden polyps, which are often missed by current techniques, Dr. Jacques Van Dam said at the annual Digestive Disease Week.
With these new techniques, patients may be more willing to be screened as well, said Dr. Van Dam of Stanford (Calif.) University. He reviewed six studies with 465 patients who underwent two colonoscopies on the same day. The results showed that physicians missed 2.1% of polyps 10 mm in diameter or larger, 13% of polyps measuring 5–10 mm, and 26% of adenomas less than 5 mm in diameter (Am. J. Gastroenterol. 2006;101:343–50).
Colorectal cancer screening has become increasingly important in gastroenterology. In a 2005 study, 5%–20% of all colonoscopies failed to reach the cecum (Endoscopy 2005;38:209–13). Current colonoscopic devices are prone to looping on insertion, leading to incomplete procedures and the need for sedation and analgesia. These devices require force against the colon wall to advance them to the cecum. Physicians using the devices require rigorous training.
Several investigational colonoscopy devices may increase the rate of successful colonoscopies and lessen patient discomfort, he said.
The CathCam is a disposable multilumen, wire-guided catheter. An outer segment 11 mm in diameter contains a 3-mm-diameter camera with six light-emitting diodes. The guide wire is placed via colonoscopy. In 14 volunteers with a current or previous failure of complete colonoscopy, 12 procedures reached the cecum, one was blocked by a stricture, and one patient dropped out. All patients were sedated with 2–5 mg of midazolam. The average time to reach the cecum was 24 minutes. In nine cases, the new device helped to identify important findings that had been missed with previously failed colonoscopies (Endoscopy 2005;38:209–13).
The Aer-O-Scope, a self-propelling, self-navigating disposable device, allows successful imaging of the colon independent of the clinician's skill. In a test that included standard colonoscopy, the device reached the cecum in 10 of 12 healthy volunteers, in a mean time of about 14 minutes (Gastroenterology 2006;130: 672–7).
A computer-assisted colonoscope made by NeoGuide Systems is propelled with the aid of a follow-the-leader algorithm, eliminating the force applied in standard colonoscopies. A prospective, nonrandomized, unblinded feasibility study was done with five physicians of various levels of experience. In all 10 consecutive patients (6 men and 4 women, age range 19–80) in the study, the device reached the cecum and enabled identification of diverticular disease in two cases and multiple colonic polyps in two cases. Polyps were removed using standard endoscopic techniques.
The Third Eye Retroscope (Avantis Medical Systems) is a disposable device used in conjunction with colonoscopy. When tested using tandem colonoscopy on latex models configured with polyps located on both sides of folds, the Third Eye identified 12% of distal side and 81% of proximal side polyps.
The PillCam Colon, a new design of the PillCam capsule that is not yet approved for U.S. use, measures 11 mm by 32 mm. The device, which is swallowed, requires no sedation or intubation. A specially developed procedure combines laxatives and prokinetic agents. The Given Diagnostic Imaging System is used for image acquisition, processing, and interpretation.
Dr. Van Dam revealed that he receives research support from, is a consultant to, and owns stock in NeoGuide Systems Inc. and Avantis Medical Systems Inc.