White Light vs Narrow Band Imagingin the Diagnosis of Right Sided Colonic Polyps in Asymptomatic Subjects Undergoing Screening Colonoscopy

Removal of colorectal adenomas prevents occurrence of cancers. It is recognized that colonoscopy can miss colorectal adenomas and early cancers. Proximal colon polyp detection rate is lower compared to distal colon detection rates. This may be partially due to the higher prevalence of flat polyps and sessile serrated adenomas (SSAs) which are harder to visualize. There is a need to further improve performance of colonoscopy. A second evaluation of the right colon within the same procedure may yield an additional detection rate of 5-10%, however retro-flexion has not proven to be superior to a second forward viewing examination. The use of chromo-endoscopy has been shown to improve detection of flat adenomas. Narrow band imaging was introduced in year 2006. It is similar to chromo-endoscopy in that it provides more mucosal details. This enables endoscopists to accurately describe the pit pattern of adenomas. NBI has been used as a substitute to chromo-endoscopy. In pooled analysis, NBI is comparable to chromo-endoscopy in their sensitivity and specificity in the diagnosis of malignant colorectal adenomas. Unfortunately, the use of NBI has not been shown to conclusively improve rate of colorectal adenoma detection. Two of 3 randomized trials that compared WLE to NBI showed a higher adenoma detection rate with the use of NBI. In a study by Rex et al., the rate was however similar with either modality. In a pooled analysis, NBI was only marginally better than WLE.

The effective use of NBI depends on the quality of bowel preparation and the experience of endoscopist. In the presence of fecal matters, NBI tends to be dark and detection of small adenomas becomes difficult. The prototype bright NBI coupled with high definition resolution is likely to overcome this drawback of original NBI.

Inclusion criteria

• Asymptomatic subjects undergoing screening colonoscopy
• age > 50.
• average risk subjects defined as those without a personal history of inflammatory bowel disease, colon adenoma or cancer or family history of FAP or Familial non-polyposis syndrome or first degree relatives having diagnosed to have colo-rectal carcinoma, no colonoscopy in past 5 years and, ability to provide a written consent to trial participation

Exclusion criteria

• unable to consent