EFFECT OF ADDING RIGHT COLON RETROFLEXION TO ONE FORWARD-VIEW EXAMINATION DURING COLONOSCOPY COMPARED WITH TWO FORWARD-VIEW EXAMINATIONS: A SYSTEMATIC REVIEW AND META-ANALYSIS

Abstract

[Background and Objectives] Preventing colon cancer-related deaths via screening colonoscopy is less effective for the right colon than for the left colon. Therefore, the right colon requires more careful examination. We investigated the efficacy and safety of right colon retroflexion during colonoscopic examination.

[Methods] Randomized controlled trials were assessed to compare two forward-view examinations against one forward-view examination with an additional retroflexion view during colonoscopic examination of the right colon. We included randomized controlled studies in which the subjects were over 18 years old and underwent colonoscopy. MEDLINE (PubMed), the Cochrane Central Register of Controlled Trials (CENTRAL), Embase, the International Clinical Trials Registry Platform (ICTRP), and Igaku Chuo Zasshi (a Japanese medical literature database) were used to search for studies from May 2017 to June 2017. We performed a meta-analysis on data extracted using a random effects model. The quality of evidence was evaluated according to the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system. The review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement．The protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO registration number: CRD 42017062538).

[Results] Only two randomized controlled trials were deemed eligible, from which 948 subjects were selected. No studies reported subsequent colon cancer-related deaths or colon cancer incidence. The risk ratio of detection of additional adenomas, sized ≥10 mm, in the right colon, detected in the second retroflexion examination in the right colon, was 0.89 (95% confidence interval [CI] 0.26-3.05, P=0.85). There was no increase in detection of additional adenomas ≥10 mm in size by adding the retroflexion view compared with two forward-view examinations. The risk ratio of detection of additional adenomas of any size in the right colon was 0.76 (95% CI 0.55-1.05, P=0.10). The detection rate of additional adenomas of any size in the retroflexion group was decreased compared with that in the two forward-view examinations group, although the difference was not significant. There were no cases of perforation or bleeding. The quality of evidence for each outcome was low.

[Limitation] Synthesizing the available research was one of the limitations in this study, because of the varying definitions of the extent of the right colon that was investigated (to the level of the hepatic flexure or the splenic flexure). A second limitation was that only two eligible articles were found.

[Conclusion] We found that there was limited evidence for the efficacy of retroflexion views of the right colon. There was no evidence of superiority of detection by adding the right-colon retroflexion view to one forward-view examination, compared with two forward-view examinations.