Research design: This is a prospective, randomized trial comparing the ADR between patients undergoing a screening colonoscopy in four different groups: 1) at least 3 minutes from the total withdrawal time dedicated to the right side of the colon, 2) at least 4 minutes from the total withdrawal time dedicated to the right side of the colon, 3) 6 minutes total withdrawal time regardless of time spent in any segment, 4) 8 minutes total withdrawal time regardless of the time spent in any segment. Randomization will be done in blocks after stratification. Four gastroenterologists and two fellows matched base on similar ADR and stratified on each arm of the study (segmental versus non-segmental withdrawal) will be performing the procedures. The estimated sample size of the four arms of the study is 400 patients.