The purpose of this study is to determine if the trendelenberg (TD) position (position in procedures that involves placing the patient at an angle so that their head is lower than their feet on the procedure bed) in select patients undergoing colonoscopy is superior than the left lateral (LL) position (patient laying on their side, traditionally used for colonoscopies) in terms of decreasing time necessary to pass the colonoscope through the left colon, and decreasing the difficulty of the procedure.

The colonoscopists will be asked to rate their prediction of difficulty of the procedure prior to the colonoscopy and to rate the ease of procedure after the colonoscopy. The clinical experience of the study investigators is that TD positioning is superior to LL positioning in patients with risk factors for having a difficult colonoscopy (thin women; those with diverticulosis- small bulging pouches present in the colon; or prior pelvic surgery).

Patients with risk factors for difficult colonoscopy will be randomized to undergo colonoscopy while positioned in the TD position or the LL position during advancement of the colonoscope through the sigmoid colon. The sigmoid colon is a section of the colon, proximal to the rectum, that is curved. The sigmoid colon is a normal component of GI tract anatomy, although due to it's shape, especially with the risk factors listed previously; can cause challenges to inserting the colonoscope.

Inclusion Criteria:

1. Personal history of pelvic surgery
2. Diverticulosis, identified by patient report or review of previous colonoscopy or imaging studies.
3. BMI < 25.

Exclusion Criteria:

1. Patients who do not meet inclusion criteria.
2. Patients who have undergone colonic resection
3. Patients with glaucoma
4. Patients with uncontrolled acid reflux disease or active nausea/vomiting.
5. Patients who are unwilling or unable to consent.
6. BMI > 30

Adults