Dose the Saline Reduce the Mucus Production When Water Exchange Colonoscopy is Used?

This is a study to compare the left colon mucus production between carbon dioxide (CO2) insufflation and water exchange (WE) colonoscopy in patients that require a routine or repeat colonoscopy. There will be four arms in this study: CO2 insufflation (control group 1), WE with water infusion (control group 2), WE with 50% saline infusion (study group 1), and WE with 25% saline infusion (study group 2). The patient will prepare himself/herself for the colonoscopy as per normal instructions and he/she will be given the information for the study at that time so that he/she can make a decision to participate in the study. The WE control group will use sterile water filling during colonoscope insertion. The study method will use saline filling during colonoscopy insertion. This study will confirm if using the saline infusion is a better method in reducing mucus production when WE colonoscopy is used.

This will be a single-site (Evergreen General Hospital, Taoyuan, Taiwan), blinded investigators, prospective randomized controlled trial (RCT). Felix W. Leung (from Sepulveda Ambulatory Care Center, Veterans Affairs Greater Los Angeles Healthcare System, North Hills, CA) will be involved in the study design, data analysis, and report preparation, but not in patient enrollment. Randomization (CO2, WE with water, WE with 50% saline, WE with 25% saline) will be based on computer generated random numbers placed inside opaque sealed envelopes. The envelope (in pre-arranged order) will be opened to reveal the code when the colonoscopist is ready to insert the endoscope to begin the examination. This will be a comparison of two different insertion methods with four arms (CO2 insufflation, WE with water, WE with 50% saline, WE with 25% saline) to see which solution used in WE is better in reducing mucus production.

Patients who are willing to participate will sign an informed consent before starting the colonoscopy procedure. Randomization will be stratified by investigators and indication of colonoscopy (screening, surveillance, or positive fecal immunochemical test). All participating patients will receive conscious sedation during the colonoscopic examination. Randomization (prepared by statistics consultant) will be carried out by the method of random permuted block design (based on computer generated random numbers) with variable block of 3 and 6.

Control method: One arm of the study will include colonoscopy with water infusion during insertion as the control method. Residual air in the colon will be removed and sterile water will be infused to guide insertion through an airless lumen. Infused water will be removed by suction, along with residual fecal debris, predominantly during insertion. Another arm of the study will include colonoscopy with CO2 insufflation during insertion as an additional control method.

Study method: Two arms of the study will include colonoscopy with saline infusion of different strength, i.e., 50% saline and 25% saline, during insertion. Residual air in the colon will be removed and saline solution will be infused to guide insertion through an airless lumen. Infused saline will be removed by suction, along with residual fecal debris, predominantly during insertion.

Eligibility Criteria:
Inclusion Criteria:

* Male and female 20-75 years of age
* Positive screening for Fecal Immunochemical Test (FIT)
* Subjects willing to undergo routine screening and surveillance colonoscopy

Exclusion Criteria:

* Patients who decline to provide informed consent
* Patients known to have colonic obstruction, active inflammatory bowel disease, or active GI bleeding requiring interventions
* Patients known to have prior history of colonic resection
* Patients with genetic colorectal syndromes
* Patients who are scheduled for therapeutic colonoscopy (e.g., hemostasis, removal of large polyp)
* Patients with American Society of Anesthesiology classification of physical status grade 3 or higher