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Water-aided colonoscopy: a systematic review

BACKGROUND

Water-aided methods for colonoscopy are distinguished by the timing of removal of infused water, predominantly during withdrawal (water immersion) or during insertion (water exchange).

OBJECTIVE

To discuss the impact of these approaches on colonoscopy pain and adenoma detection rate (ADR).

DESIGN

Systematic review.

SETTING

Randomized, controlled trial (RCT) that compared water-aided methods and air insufflation during colonoscope insertion.

PATIENTS

Patients undergoing colonoscopy.

INTERVENTION

Medline, PubMed, and Google searches (January 2008-December 2011) and personal communications of manuscripts in press were considered to identify appropriate RCTs.

MAIN OUTCOME MEASUREMENTS

Pain during colonoscopy and ADR. RCTs were grouped according to whether water immersion or water exchange was used. Reported pain scores and ADR were tabulated based on group assignment.

RESULTS

Pain during colonoscopy is significantly reduced by both water immersion and water exchange compared with traditional air insufflation. The reduction in pain scores was qualitatively greater with water exchange as compared with water immersion. A mixed pattern of increases and decreases in ADR was observed with water immersion. A higher ADR, especially proximal to the splenic flexure, was obtained when water exchange was implemented.

LIMITATIONS

Differences in the reports limit application of meta-analysis. The inability to blind the colonoscopists exposed the observations to uncertain bias.

CONCLUSION

Compared with air insufflation, both water immersion and water exchange significantly reduce colonoscopy pain. Water exchange may be superior to water immersion in minimizing colonoscopy discomfort and in increasing ADR. A head-to-head comparison of these 3 approaches is required.

Removal of infused water predominantly during insertion (water exchange) is consistently associated with a greater reduction of pain score - review of randomized controlled trials (RCTs) of water method colonoscopy

INTRODUCTION: Variation in the outcomes in RcTs comparing water-related methods and air insufflation during the insertion phase of colonoscopy raises challenging questions regarding the approach. This report reviews the impact of water exchange on the variation in attenuation of pain during colonoscopy by water-related methods. METHODS: Medline (2008 to 2011) searches, abstracts of the 2011 Digestive Disease Week (DDW) and personal communications were considered to identify RcTs that compared water-related methods and air insufflation to aid insertion of the colonoscope. Results: Since 2008 nine published and one submitted RcTs and five abstracts of RcTs presented at the 2011 DDW have been identified. Thirteen RcTs (nine published, one submitted and one abstract, n=1850) described reduction of pain score during or after colonoscopy (eleven reported statistical significance); the remaining reports described lower doses of medication used, or lower proportion of patients experiencing severe pain in colonoscopy performed with water-related methods compared with air insufflation (Tables 1 and 2). The water-related methods notably differ in the timing of removal of the infused water - predominantly during insertion (water exchange) versus predominantly during withdrawal (water immersion). Use of water exchange was consistently associated with a greater attenuation of pain score in patients who did not receive full sedation (Table 3). CONCLUSION: The comparative data reveal that a greater attenuation of pain was associated with water exchange than water immersion during insertion. The intriguing results should be subjected to further evaluation by additional RcTs to elucidate the mechanism of the pain-alleviating impact of the water method.

Is there a place for sedationless colonoscopy?

Usedated colonoscopy is routinely available in many parts of the world. In the US, only educated professionals appear to be knowledgeable enough to request the unsedated option. Colonoscopists have also been willing to perform unsedated colonoscopy when a patient presents without an escort after undergoing bowel purge preparation. While the actual side-effects of sedation are minimal, the escort requirement and time burden of sedation are barriers to the uptake of screening colonoscopy in the US. The recent trend of deep sedation with propofol for screening colonoscopy increases the efficiency of the colonoscopists at significant costs (e.g. anesthetist reimbursement). The options of as needed and on demand sedation permit patients to complete colonoscopy without sedation. The latter appears to be potentially less coercive. Nurses with experience in the unsedated options recognize the benefit of the quick turn-around of the examination room and shortened occupancy of the recovery area. Discharge planning can be optimized due to absence of amnesia. Patients completing unsedated colonoscopy have given their endorsement of the options. Pain and discomfort continue to limit the success rate of cecal intubation to about 80%. A recently described water method (warm water infusion in lieu of air insufflation combined with removal of all residual colonic air by suction and residual feces by water exchange) has the potential of decreasing procedural discomfort and enhancing cecal intubation in unsedated colonoscopy. The availability of the novel water method assures colonoscopists that high success rate of cecal intubation can be achieved in the unsedated patients.