The investigators did a pilot study with 150 subjects to check the mean no.of adenomas per colonoscopy, no.of adenomas detected in the right colon during the second look and to estimate the recruitment rate. Based on those results the investigators started this study with a large sample size. The investigators are planning to do an interim analysis after recruiting 450 subjects (30% of total enrollment). The results of the analysis will determine whether the investigators complete recruitment of the initially approved sample size of 1500 subjects.