Cap-fitted Colonoscopy: a Randomized, Tandem Colonoscopy Study of Adenoma Miss Rates

This is a test in which a thin, black, flexible tube with a lighting system on the end is passed through the anus, into the rectum, in order to examine the large bowel or intestine, also called the colon. Colonoscopy is a very good test for examining the colon for polyps (warty growths that can turn into cancer), but it is not perfect. In fact, about 30% of polyps that are under 5 mm (about 1/5 of an inch) in size are missed during colonoscopy because they are hiding behind folds and bends in the colon. This research study is being done to determine if performing colonoscopy with a cap on the tip of the colonoscope will reduce the miss rate for polyps. A cap is a clear plastic hood that fits on the tip of the colonoscope and sticks out about 1/3 of an inch. During colonoscopy, the cap can be pressed against a fold or ridge in order to flatten it, so that the lining on the other side can be more easily seen. This may reduce the miss rate for colon polyps.

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.

Subjects will be randomized to either initial cap-fitted colonoscopy or regular colonoscopy. Patients in the initial regular arm, will undergo cap-fitted colonoscopy for their second, tandem examination. Patients in the initial cap-fitted arm, will under undergo regular colonoscopy (without the cap) for their second, tandem examination.

Cap Fitted Colonoscopy (CFC) may significantly reduced miss rates for colorectal adenomas, specifically for small adenomas. This study is the first North American study of any design and the largest tandem study of CFC. CFC is a safe, simple, and inexpensive technology that could improve the reliability of colonoscopy in detecting colorectal neoplasia. Additional study of CFC in Western populations is warranted.

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.

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.

Inclusion Criteria: 50 years of age or older, undergoing scheduled colonoscopy and able to give informed consent. Exclusion Criteria: Previous surgical resection of the colon or rectum American Society of Anesthesiology class III or higher Inflammatory bowel disease Current use of anticoagulants.

Hewett DG, Rex DK. Cap-fitted colonoscopy: a randomized, tandem colonoscopy study of adenoma miss rates. Gastrointest Endosc. 2010 Oct;72(4):775-81. doi: 10.1016/j.gie.2010.04.030. Epub 2010 Jun 25.