A proof-of-principle, prospective, randomized, controlled trial demonstrating improved outcomes in scheduled unsedated colonoscopy by the water method

Gastrointest Endosc. 2010 Oct;72(4):693-700. doi: 10.1016/j.gie.2010.05.020. Epub 2010 Jul 8.


Background: An observational study in veterans showed that a novel water method (water infusion in lieu of air insufflation) enhanced cecal intubation and willingness to undergo a repeat scheduled unsedated colonoscopy.

Objective: To confirm these beneficial effects and significant attenuation of discomfort in a randomized, controlled trial (RCT).

Design: Prospective RCT, intent-to-treat analysis.

Setting: Veterans Affairs ambulatory care facility.

Patients: Veterans undergoing scheduled unsedated colonoscopy.

Interventions: During insertion, the water and traditional air methods were compared.

Main outcome measurements: Discomfort and procedure-related outcomes.

Results: Eighty-two veterans were randomized to the air (n = 40) or water (n = 42) method. Cecal intubation (78% vs 98%) and willingness to repeat (78% vs 93%) were significantly better with the water method (P < .05; Fisher exact test). The mean (standard deviation) of maximum discomfort (0 = none, 10 = most severe) during colonoscopy was 5.5 (3.0) versus 3.6 (2.1) P = .002 (Student t test), and the median overall discomfort after colonoscopy was 3 versus 2, P = .052 (Mann-Whitney U test), respectively. The method, but not patient characteristics, was a predictor of discomfort (t = -1.998, P = .049, R(2) = 0.074). The odds ratio for failed cecal intubation was 2.09 (95% CI, 1.49-2.93) for the air group. Fair/poor previous experience increased the risk of failed cecal intubation in the air group only. The water method numerically increased adenoma yield.

Limitations: Single site, small number of elderly men, unblinded examiner, possibility of unblinded subjects, restricted generalizability.

Conclusions: The RCT data confirmed that the water method significantly enhanced cecal intubation and willingness to undergo a repeat colonoscopy. The decrease in maximum discomfort was significant; the decrease in overall discomfort approached significance. The method, but not patient characteristics, was a predictor of discomfort. (Clinical trial registration number NCT00747084).

Publication types

  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenoma / diagnosis
  • Aged
  • Air
  • Cecum
  • Colonic Neoplasms / diagnosis
  • Colonoscopy / adverse effects
  • Colonoscopy / methods*
  • Conscious Sedation
  • Humans
  • Insufflation / methods*
  • Intention to Treat Analysis
  • Intubation, Gastrointestinal
  • Male
  • Middle Aged
  • Patient Satisfaction
  • Prospective Studies
  • United States
  • Veterans
  • Water / administration & dosage


  • Water

Associated data

  • ClinicalTrials.gov/NCT00747084