Uncontrolled data suggest that warm water infusion (WWI) instead of air insufflation (AI) during the insertion phase of unsedated colonoscopy improves patient tolerance and satisfaction.

We tested the hypothesis that water could increase the proportion of patients able to complete unsedated colonoscopy and improve patient tolerance compared with the conventional procedure.

Randomized, controlled trial.

Single center, community hospital.

Consecutive outpatients agreeing to start colonoscopy without premedication.

Patients were randomly assigned to either WWI or AI insertion phase of colonoscopy. Sedation and/or analgesia were administered on patient request if significant pain or discomfort occurred.

Percentage of patients requiring sedation/analgesia. Pain and tolerance scores were assessed at discharge by using a 100-mm visual analog scale.

A total of 230 subjects (116 in the WWI group and 114 in the AI group) were enrolled. Intention-to-treat analysis showed that the proportion of patients requesting sedation/analgesia during the procedure (main outcome measurement) was 12.9% in the WWI group and 21.9% in AI group (P = .07). Cecal intubation rates were 94% in the WWI group and 95.6% in the AI group (P = .57). Median (interquartile range) scores for pain were 28 (12-44) and 39 (14-54) in WWI and AI groups, respectively (P = .05); corresponding figures for tolerance were 10 (3-18) and 14 (5-42), respectively (P = .01). The adenoma detection rates were 25% and 40.1% for the WWI and AI groups, respectively (P = .013).

Single-center study, endoscopists not blinded to randomization.

WWI instead of AI is not associated with a statistically significant decrease in the number of patients requiring on-demand sedation, although it significantly improves the overall patient tolerance of colonoscopy. The finding of a lower adenoma detection rate in the WWI group calls for further evaluations. (Clinical trial registration number: NCT00905554).