Results of a second examination of the right side of the colon in screening and surveillance colonoscopy: a systematic review and meta-analysis

BACKGROUND: Screening colonoscopy is less effective in preventing proximal colon cancers than distal colon cancers. A repeat examination of the right side of the colon may increase the lesion detection. The study aimed to assess the results of a second examination of the right side of the colon with forward-view or retroflexion colonoscopy performed immediately after the initial examination. MATERIALS AND METHODS: We carried out a meta-analysis of all primary studies that performed a second examination of the right side of the colon with forward-view or retroflexion colonoscopy performed immediately after the initial examination. RESULTS: Six cohorts of five studies with 4155 participants were included in the final study. The adenoma detection rate (ADR) was 28.8% of the combined examinations compared with 24.1% of the single examination (P<0.001), for a pooled odds ratio of 1.34 [95% confidence interval (CI): 1.13-1.59]. For retroflexion assessment, ADR was achieved in 25.4% patients in the combined group, compared with 22.3% in the single examination group (P=0.002), for a pooled odds ratio of 1.19 (95% CI: 1.06-1.33). For forward-view assessment, ADR was achieved in 46.0% patients in the combined group, compared with 33.5% in the single examination group (P<0.001), for a pooled odds ratio of 1.76 (95% CI: 1.40-2.22). CONCLUSION: For ADR of the right side of the colon, a repeat examination could lead to a modest improvement in the detection of lesions in the proximal colon, irrespective of forward-view or retroflexion assessment.