Comparative effectiveness of water infusion versus air insufflation in colonoscopy: a meta-analysis.Jun Wu, Bing Hu. Colorectal Disease 2012 .Manuscript online: 14 AUG 2012 Aim: Colonoscopy with air insufflation is known to result in abdominal pain and discomfort. Recently, some trials reported that water infusion in lieu of air insufflation could decrease patient discomfort. We aimed to determine the effectiveness of water infusion during colonoscopy through a meta-analysis. Method: Original articles and abstracts published up to October 2011 were searched in Medline, EMBASE, Cochrane Library Database and momentous Meeting Abstracts. Clinical appraisal and data extraction were conducted by two reviewers independently. Statistical analysis was performed by meta-analysis using fixed effects model or random effects model. Results: Seven studies containing 872 patients were included. Meta-analysis showed that water infusion group had less patients requiring abdominal compression or position change (RR 0.73, 95%CI [0.59,0.91]), a lower mean pain score (RR -1.10, 95%CI[-1.26,-0.95]), lower maximum pain score (RR -2.34, 95%CI[-2.92,-1.76]) and fewer patients requiring on-demand sedation (RR 0.45, 95%CI[0.31,0.66]) than air insufflation group during colonoscopy. There were no significant difference in caecal intubation rate, caecal intubation time, total procedure time and adenoma detection rate. Conclusion: Water infusion significantly decreases patient discomfort and abdominal pain during colonoscopy without affecting operation time and intubation success rate.