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 insufflation, 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 specific to water exchange, but could account for all or part of the better results with water exchange. Additional controlled investigation is needed to define the benefits of water exchange compared with water immersion.
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