The goal of this study is to compare two FDA approved distal colonoscope attachment devices, in order to identify which device can increase adenoma detection rate the most without increasing procedure time or risk.

Although mortality from colon cancer is decreasing, it remains the second leading cause of cancer related death in the United States. There are multiple factors contributing to this decrease, such as increased awareness, improving screening techniques, etc.

Of the available modalities approved for colon cancer screening in the United States, colonoscopy is considered the gold standard. Colonoscopy has the advantage of being both diagnostic and therapeutic, allowing the removal of pre-cancerous polyps, before the polyps can transform into cancer. Colonic polyps can occur at any location from the rectum to the cecum. Colonoscopy has been shown to be more effective in decreasing incidence of cancer in the left colon but remains limited in the detection of right sided polyps /lesions 2. This difference based on location is thought to be due to several reasons. Typically the right side of the colon is less clean than the left side during colonoscopy, thereby impairing visualization of polyps. This problem has been overcome by incorporating a "split bowel preparation", which has not become standard of care. However, the problem of not being able to visualize polyps behind folds seen in the colon persists despite improvements in the quality of cleansing of the colon. Various endoscopic technologies have been introduced with the goal of assisting with the manipulation of such colonic folds, and thereby reducing chances of missing polyps behind fold. Two such colonoscope assisted devices including the distal transparent cap and the Endocuff endoscopic overtube.

The Endocuff overtube is a small device with flexible arms arranged in 2 rows. Each row has 8 short, soft arms projecting away from the device. These arms are used to peel back the colonic folds without causing physical damage to enable visualization behind colonic folds. The use of Endocuff overtube has shown promising results in terms of cecal intubation rate and time as well as adenoma detection rates 3.

The transparent cap attachment is a clear plastic device that fits at the end of the colonoscope and extends a short distance past the tip of the colonoscope. It aids in the manipulation of folds and in maintaining a suitable distance from the mucosa, with the goal of improving visualization. Although some studies comparing cap fitted colonoscopy to standard (non- attachment) colonoscopies have shown improved adenoma detection 4, others have shown no significant benefit 5.

Although, these devices have been compared with conventional colonoscopies (i.e without any distal attachment), to the investigator's knowledge, there are currently no studies that have compared these two distal colonoscope attachment devices head-to-head, and none has specifically evaluated effects on detection of right sided adenomas. Also, here at UCDavis, these devices are being used specifically in diagnostic colonoscopies for removal of large polyps and the choice of which specific device is used depends on level of comfort of the advanced endoscopist. The endoscopists participating in the investigators' study do not currently use these devices as part of their routine colonoscopies, thus it is important to provide head to head comparison of these devices to help guide management practice.

Therefore, the investigators' goal is to compare the Endocuff overtube assisted, transparent cap fitted, and non-cap fitted (standard) colonoscopy in patients presenting to UC Davis Medical Center for screening colonoscopies.

In addition, 2 of the 3 investigators will employ the water exchange method during for all arms of the trial, while the other investigator will employ the conventional air method of colonoscopy.

Inclusion Criteria:

• At least 50 years old
• Presenting for a screening or surveillance colonoscopy at UC Davis Endoscopy Suites

Exclusion Criteria:

• Age less than 50 years
• Prior history of colon cancer
• Patients with inflammatory bowel disease
• Patients suspected to have colon cancer based on non invasive tests such as stool tests for hemoglobin or DNA, or imaging finding suggestive of colon cancer (CT or barium enema).
• Patients undergoing colonoscopy for evaluation of symptoms such as abdominal pain, rectal bleeding, diarrhea, constipation, etc, or patient with iron deficiency anemia suspected to be due to ongoing bleeding inside the colon
• Patients with family history of colon cancer in 1st degree relative below the age of 60
• Patients with family history of hereditary polyposis syndromes such as Lynch syndrome, familial adenomatous polyposis etc, which are associated with an increased risk of colon cancer
• Patients unable to consent
• Pregnant patients
• Incarcerated patients
• Non-English speakers

8 months