Editorial: Water Exchange vs. Water Immersion During Colonoscope Insertion

Abstract

Water exchange (water infusion with water removal primarily during insertion) and water immersion (water infusion with water removal during withdrawal) reduce patient discomfort during colonoscope insertion compared with air insuffl ation, and represent a major achievement in colonoscopy. Hsieh et al. found that water exchange, relative to water immersion, resulted in more painless insertions to the cecum and improved adenoma detection in the right colon. However, water exchange is also associated with better bowel cleansing and longer insertion and procedure times. These factors are not specifi c to water exchange, but could account for all or part of the better results with water exchange. Additional controlled investigation is needed to defi ne the benefi ts of water exchange compared with water immersion. Am J Gastroenterol 2014; 109:1401 -1403 doi: 10.1038/ajg.2014 Water infusion during colonoscope insertion is increasingly popular. Water infusion, as it is generally understood, involves shutting the insuffl ation gas off and fi lling the colon only with water during insertion. Compared with air insuffl ation, water infusion reduces pain in patients who are lightly sedated or unsedated ( 1 -4 ). Water infusion can facilitate cecal intubation in patients with redundant colons ( 5 ). Many experienced endoscopists, myself included, convert from gas to water when they encounter a challenging sigmoid colon and believe that water helps them pass tight turns. Water infusion should reduce the risk of cecal barotrauma, which is greatest in patients with narrowed or angulated sigmoid colons. When polypectomy in the sigmoid colon is challenging because of " spasm " (the sigmoid is oft en dependent and will not retain insuffl ated gas), fi lling the sigmoid with water provides luminal distention and allows easy underwater polyp visualization and snaring ( 6 ). Water infusion is safe ( 7,8 ), cheap, and makes intuitive sense. Th us, whereas gas insuffl ation moves the sigmoid into the mid abdomen and makes angulations in the sigmoid more acute, water sinks and straightens the sigmoid in patients in the left lateral decubitus position. To the extent that bowel preparation is suboptimal when colonoscopy begins, water infusion improves cleansing. My anecdotal impression is that the only downsides of water infusion are that it takes time to remove the water and that during withdrawal some patients seem to have excess mucus in the rectosigmoid aft er water infusion. Considering the various benefi ts, water infusion is a major achievement in colonoscopy.Th e process or basic method for infusing water during intubation has been subdivided into two categories termed " water immersion " and " water exchange " ( 9 ). Water immersion means infusing water solely for the purpose of expanding the lumen and intubating the cecum, with suctioning of the water occurring during withdrawal. In water exchange, the cecal intubation process proceeds more slowly, with the infused water suctioned during insertion rather than during wi...

Water exchange colonoscopy increases adenoma detection rate: a systematic review with network meta-analysis of randomized controlled studies

“…One major drawback for the diffusion of WE has been its long insertion time when compared with the usual gas insufflation colonoscopy, especially considering that the learning curve needs about 100 procedures to achieve sufficient skill, which may hamper its routine implementation. 19,39,40 Our data show that WE cecal intubation time was significantly longer than that of the other techniques (ie, about 3 to 5 minutes), and yet withdrawal time was similar. When evaluating this additional time, it should be considered that in all selected studies, the WE technique was performed by adequately trained and motivated endoscopists; therefore, outside controlled studies, in Figure 1.…”

Impact of water exchange colonoscopy on endoscopy room efficiency: a systematic review and meta-analysis

“…Although there is no systematic survey to document the uptake of WE colonoscopy in clinical practice, an editorial focused on the procedure time presumed this as a major deterrent to its more widespread use. 9 Subsequent commentaries continued to express concern over the prolonged insertion time, 10 and a recent editorial on the subject 11 provided insight that, at least in the United States, the widespread use of deep sedation during colonoscopy may hinder or delay the wider implementation of WE colonoscopy. Most RCTs included in our study showed comparable insertion and total procedure times between WE and GAS; in those studies that reported a significantly longer insertion time, the mean increase was only 3.9 minutes.…”

“…[2][3][4][5][6][7] This has a negative impact on room turnaround efficiency and contributed to hampering its wider adoption in clinical practice. [9][10][11] A meta-analysis 7 reported that despite the longest cecal intubation time with WE, it is still comparable with other insertion methods. However, absolute numbers to show the magnitude of the difference were not reported.…”

Comparing adenoma and polyp miss rates for total underwater colonoscopy versus standard CO2: a randomized controlled trial using a tandem colonoscopy approach

“…All of these studies have used 2 different techniques, water exchange (WE) and water immersion (WI). WE, in particular has been shown to increase adenoma detection but it is not clear whether the reason is better mucosal visualization with the water or other attendant features associated with WE 17 . In particular, WE may dramatically change the quality of the bowel preparation, allowing for more adenomas to be detected.…”

“…The use of water during colonoscopy may improve adenoma detection through several possible mechanisms 17 . It may help to further clear the bowel of any residual stool.…”