Prospective Randomized Controlled Trial Comparing Water and Air Colonoscopy in a Community Based Setting

• Proximal Adenoma detection [ Time Frame: Data collected when pathology is available, typically 3-10 days after the patient's procedure. Data is collected only once per patient. ] [ Designated as safety issue: No ]
  Presence of adenoma detected anywhere between the cecum and the splenic flexure
  
  

• Total adenoma detection [ Time Frame: Data collected when pathology is available, typically 3-10 days after the patient's procedure. Data is only collected once per patient. ] [ Designated as safety issue: No ]
  Adenoma detection anywhere in the colon during colonoscopy.
  
  
• Sedation requirements [ Time Frame: This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length. ] [ Designated as safety issue: No ]
  The amount of sedation required to complete the patient's colonoscopy.
  
  
• Total procedure time [ Time Frame: This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length. ] [ Designated as safety issue: No ]
  The total time it takes to complete colonoscopy.
  
  
• Cecal intubation time [ Time Frame: This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length. ] [ Designated as safety issue: No ]
  The time it takes to reach the cecum during colonoscopy.
  
  
• Patient position change during procedure [ Time Frame: This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length. ] [ Designated as safety issue: No ]
  The need for patient's position to be changed from left lateral to other positions, to enable advancement of the colonoscope forward.
  
  
• Use of colonoscope stiffener during procedure [ Time Frame: This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length. ] [ Designated as safety issue: No ]
  The need to stiffen the colonoscope to enable to forward movement of the scope during procedure
  
  
• Abdominal pressure by assistant during procedure [ Time Frame: This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length. ] [ Designated as safety issue: No ]
  Need for abdominal pressure by endoscopist's assistant during procedure to enable forward movement of colonoscope.
  
  
• Length of colonoscope at time of cecal intubation [ Time Frame: This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length. ] [ Designated as safety issue: No ]
  Assessment of length of the colonoscope inserted into the colon to reach the cecum.
  
  
• Procedure-related pain score [ Time Frame: Data collected during and post procedure after recovery from sedation, which is usually within 1 hour post procedure ] [ Designated as safety issue: No ]
  Assessment of discomfort due to the procedure, as possible during procedure, and post procedure after recovery from sedation, being cognizant of limitations posed by sedation and attendant amnesia.
  
  
• Reason for air insufflation, and length of colon when air insufflation started, while performing water colonoscopy [ Time Frame: This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length. ] [ Designated as safety issue: No ]
  Assessment of percentage of patient requiring air insufflation when water colon fails to open colonic lumen, and site of colon where this is most likely to happen.
  
  
• Volume of water used during water colonoscopy [ Time Frame: This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length. ] [ Designated as safety issue: No ]
  Assessment of volume of water introduced into the colon during procedure.
  
  
• Patient perception regarding air and water colonoscopy [ Time Frame: This will be collected at their procedure appointment which is expected to be 2 to 3 hours in length. ] [ Designated as safety issue: No ]
  Assessment of patient's perception about the 2 methods of colonoscopy.
  
  

Screening colonoscopy with removal of pre-cancerous adenomas was recently shown to result in a 53% reduction in mortality from colon cancer. While this clearly validates the practice of screening colonoscopy, missed adenomas, especially in the proximal colon, defined as including cecum, ascending colon, and transverse colon, remains a concern. This was demonstrated in a study of 183 patients who underwent back-to-back colonoscopies. In this population the overall miss rate for adenomas was 24% with proximal adenomas missed more often (27%) than left colon adenomas (21%). Another study looked at 4192 patients in the SEER (Surveillance, Epidemiology, and End Results) Medicare database who developed "interval cancers", that is colon cancer in a patient who had a colonoscopy done in the previous 6-36 months. These interval cancers were predominantly in the proximal colon (Proximal 68%, Distal 19.5%, rectum 10.4%, and unspecified 2.1%). This also suggests that pre-cancerous lesions are being missed in the proximal colon. As such a method that can increase proximal adenoma detection rate would be a welcome change.

One such emerging technique which shows promise for improving adenoma detection rate is water colonoscopy. In one of the early studies employing the water method a trend towards a higher ADR in the water method group was recognized (37% vs. 26%). The observation prompted a retrospective analysis of 1178 cases of screening and surveillance colonoscopy performed by a single endoscopist at the Sacramento VAMC, which showed an overall ADR (presence of at least one adenoma) of 27% with air colonoscopy whereas that for the water method colonoscopy was 35% (p=0.007). In a subsequent combined analysis of two prospective RCT of air vs. water colonoscopy for screening and surveillance using scheduled unsedated colonoscopy [5] and on-demand sedation [6], more patients were found to have at least one diminutive adenoma in the proximal colon in the water method group than in the air group (28% vs. 14%, respectively, p=0.0298). Another quasi randomized study of screening patients performed at Phoenix VAMC using high definition equipment confirmed a significantly higher overall ADR with the water method (n=177) compared with the air method (n=191) (57% vs. 46%) (p=0.03). The odds of detecting an adenoma was 81% higher with the water method (OR 1.81; 95% CI: 1.12-2.90) and independent of age, body mass index (BMI), current smoking and alcohol use, withdrawal time & quality of bowel preparation. In the proximal colon ADR was significantly higher in patients examined with the water method than with air method (46% vs. 35%) (p=0.03), particularly for adenomas <10 mm in size (38% vs. 25%) (p=007). These encouraging preliminary data reflect the potential benefits of water method colonoscopy.

Our current research question is whether this benefit is seen in a community based population as opposed to the VA population which is mostly male and Caucasian.

The investigators plan to perform a prospective, randomized controlled trial comparing proximal adenoma detection rate between a water immersion colonoscopy group and an air colonoscopy group. The investigators intend to employ scheduled sedation, instead of on-demand sedation, to continue the current protocol in place at our institution.