Standard method of colonoscopy is to insert the colonoscope rapidly to reach the cecum, with careful inspection and polypectomy during the withdrawal phase. However, small polyps (e.g. <1cm) seen during insertion phase are difficult to find during withdrawal phase. Also, colon is in different conformation during insertion and withdrawal phases. We think careful inspection and polypectomy during both insertion and withdrawal can improve adenoma detection rate.

Inclusion Criteria:

• Patient undergoing screening or surveillance colonoscopy

Exclusion Criteria:

• Previous colorectal resection, Polyposis syndrome, Inflammatory bowel disease