Compared with the conventional (air) method, patients examined by the study (water) method have lower pain scores and require less medication but have similar cecal intubation rate and willingness to repeat future colonoscopy.

Background: A novel water method permitted 52% of patients accepting on-demand sedation to complete colonoscopy without medications and significantly increased successful cecal intubation from 76% to 97% in patients accepting scheduled unsedated colonoscopy.

Aim: To perform a randomized controlled trial comparing air insufflation (conventional method) vs. water infusion in lieu of air (study method) colonoscopy in minimally sedated patients.

Hypothesis: Compared with the conventional method, patients examined by the study method have lower pain scores and require less medication but have similar cecal intubation rate and willingness to repeat future colonoscopy.

Setting: Outpatient colonoscopy in a single VA hospital Methods: After informed consent and standard bowel preparation, patients received pre-medications administered as 0.5 increment of Fentanyl (25 μg) and 0.5 increment of Versed (1 mg) plus 50 mg Diphenhydramine. The conventional and the study method for colonoscopy were implemented as previously described. Additional pain medications were administered at the patients' request.

Outcome measures: Increments of medications, pain scores, cecal intubation and willingness to repeat colonoscopy.

Limitations: Single VA site, older male population

Inclusion Criteria:

• healthy individual 50 years or older
• eligible for colorectal cancer screening or surveillance

Exclusion Criteria:

• patients who do not understand or failed to sign informed consent