The aim of this prospective randomized controlled trial is to assess the efficacy of cap-attached colonoscopy to improve cecal intubation in comparison with regular colonoscopy for trainees.

Colorectal cancer is one of the major malignancies in western countries and also in Japan. Therefore , the demand for total colonoscopy (TCS) has risen remarkably. However, failure to reach the cecum occurs in up to 10 % of cases.

A difficult colonoscopy procedure will often be associated with more complications, and require heavier sedation to alleviate patient's discomfort.

Auxiliary devices that could facilitate the examination would be needed. A cap is a simple device that can be attached to the tip of a colonoscope. The advantage of the cap in getting a good view might be helpful in cecal intubation by depressing the folds and also by keeping an appropriate distance between the colonoscope lens and colonic mucosa. We speculated that inexperienced colonoscopists would obtain greater benefit from cap-attached colonoscopy.

Inclusion Criteria:

• Patients who undergo colonoscopy examination

Exclusion Criteria:

• Known to have colonic stricture or obstructing tumor from the results of other investigations such as CT scan or barium enema
• Presence of acute surgical conditions such as severe colitis, megacolon, ischemic colitis and active gastrointestinal bleeding ・Patients who diagnosed as inflammatory bowel disease