Endoscope-connected water pump with high flow rates improves the unsedated colonoscopy performance by water immersion method.

Objectives: The aim of this study was to determine if different water pump flow rates influence the insertion time of water immersion method in unsedated patients. We tested the hypothesis that high flow rate (HFR) is more effective than low flow rate (LFR) in facilitating insertion. Clinical registration number: NCT01869296.

Methods: Consecutive symptomatic patients without prior abdominal surgery were consented and enrolled. They were randomized to an HFR (10.4 mL/s) or LFR (1.7 mL/s) group. The patients were not informed about the flow rate of the water pump (single blinded). Patients underwent unsedated colonoscopy examination with standard colonoscope. Demographic and procedural parameters were recorded. Data were analyzed with Student's t -test or Chi-square test as appropriate.

Results: A total of 132 patients (66 in HFR and 66 in LFR group) were recruited. The HFR group showed significantly shorter cecal intubation time (12.5±6.2 min in HFR vs 16.3±7.3 min in LFR, p =0.004), shorter time to pass rectosigmoid (3.6±2.2 min in HFR vs 6.2±4.6 min in LFR, p <0.001), and lower pain score (4.2±2.8 in HFR vs 5.3±2.6 in LFR, p =0.024). The cecal intubation rate was not significantly different (87.9% in HFR vs 80.3% in LFR, p =0.34), and 29 (14 in HFR and 15 in LFR) patients with signs of colon redundancy were successfully intubated to the cecum after repeated loop reduction and position changes.

Conclusion: Compared to LFR, HFR of the water infusion pump significantly reduced colonoscopy insertion time and pain score in unsedated patients. Significantly shorter time to pass the rectosigmoid appeared to play a contributory role.