Patient will undergo tandem colonoscopy on the same day using propofol sedation. Patients will undergo one colonoscopy without the cap and a second colonoscopy with the cap on. We will endeavor to keep the total examination time equal between the groups and approximately six minutes. The order in which patients receive the two colonoscopies (i.e. cap or without cap first) will be randomized. Any polyps detected during the first colonoscopy will be removed during that procedure. During the withdrawal phase, the time for examination will be measured with a stopwatch, and the stopwatch will be stopped at any time a polyp is located and restarted when the polyp has been removed and retrieved. The stopwatch will also be stopped for suctioning fluid or washing debris from the colon surface. Any polyp detected and removed during the first colonoscopy will be counted as the detection for that procedure. During the second colonoscopy, all polyps will also be removed when detected. Any polyp identified and removed during the second procedure will be counted as a miss for the first procedure. All polyps will be sent separately for pathologic evaluation. The time required to remove and retrieve polyps with and without the cap on will be measured using a stopwatch as a secondary end point. The primary end point will be the miss rate for colonoscopy with the cap and colonoscopy without the cap.