The purpose of this study is to demonstrate efficacy of the Avantis Third Eye Retroscope auxiliary imaging system.

The primary objective of this study is to assess the degree to which incorporating the Third Eye Retroscope auxiliary imaging system in a screening colonoscopy setting results in the detection of additional polyps.

Specifically, the primary goals are to estimate (1) the proportion of polyps detected under this protocol that would have been missed without the Third Eye Retroscope, and (2) the proportion of patients found under this protocol to have polyps who would have incorrectly been classified as polyp-free had the Third Eye Retroscope not been used.

THE STUDY DEVICE:

The Third Eye Retroscope is a thin, flexible probe that can be inserted in a standard colonoscope in order to display very detailed images of the colon tissue. It contains a miniature video camera that allows the doctor to see an additional point of view that looks backward while the regular colonoscope and study device are moved together through the length of the colon.

For you to be eligible to take part in this study, your doctor will check to be sure you have no medical conditions that would increase your risk of having any complications as a result of having the study device used during your colonoscopy.

STUDY PROCEDURES:

If you are found to be eligible to take part in this study, your doctor will perform your colonoscopy exam in the usual manner except that the Third Eye Retroscope device will be used during the exam as well. Your doctor will insert the colonoscope into your rectum in the usual manner and will then insert the study device down a channel inside the colonoscope. You will sign a separate consent form for the colonoscopy, which will describe the procedure and its risks in more detail.

During the exam, you will be awake. If you have chosen to use medications for conscious sedation, you will be drowsy.

FOLLOW-UP PHONE CALL:

About 48 hours (2 days) after the study procedure, you will be called by the research staff to see how you are doing. After this follow-up call, your participation in this study will be over.

This is an investigational study. The Third Eye Retroscope device is commercially available, but it is not FDA approved for this study's purpose. At this time, for this purpose, it is being used in research only. Up to 700 patients will take part in this study. Up to 100 will be enrolled at M. D. Anderson.

Inclusion Criteria:

• The patient is undergoing colonoscopy for screening purposes or for surveillance in follow-up for previous polypectomy.
• The patient is at satisfactory risk for abdominal surgery.
• The patient must understand and provide written consent for the procedure.

Exclusion Criteria:

• Patients who are <50 years or >80 years of age
• Patients who are pregnant.
• Patients with history of colonic resection.
• Patients requiring ongoing anticoagulation therapy.
• Patients with a history of severe cardiovascular, pulmonary, liver or renal disease.
• Patients with hypersensitivity to opioid analgesics.
• Patients with an active systemic infection.
• Patients with suspected chronic stricture potentially precluding complete colonoscopy.
• Patients with major psychiatric disease (dementia, schizophrenia or depression).
• Patients with diverticulitis or toxic megacolon.
• Patients with history of radiation therapy to abdomen or pelvis.
• Patients who are currently enrolled in another clinical investigation in which the intervention might compromise the safety of the patient's participation in this study.

Of the 288 registered, only 249 had a screening colonoscopy to meet inclusion in the study.

2 years