Systematic review with meta-analysis: limited benefits from early colonoscopy in acute lower gastrointestinal bleeding

Background The optimal timing of colonoscopy in acute lower gastrointestinal bleeding (LGIB) remains controversial. Aim To characterise the utility of early colonoscopy (within 24 hours) in managing acute LGIB. Methods A systematic literature search to October 2019 identified fully published articles and abstracts of randomised controlled trials (RCTs) and observational studies with control groups assessing early colonoscopy in acute LGIB. The primary outcome was rebleeding. Secondary outcomes included mortality, surgery, length of stay (LOS), definite cause of bleeding and adverse events. Odds ratios (ORs) and mean differences (MD) were calculated. Results Of 1116 citations, 4 RCTs (466 patients) and 13 observational studies with elective colonoscopy (>24 hours) as control group (1 061 281 patients) were included. No differences in rebleeding were noted between early and elective colonoscopy groups among RCTs alone (OR = 1.70; 0.79; 3.64), or observational studies alone (OR = 1.20; 0.69; 2.09). No other significant between-group differences in outcomes were found when restricting the analysis to RCTs. Among observational studies only, early colonoscopy was associated with lower rates of all-cause mortality (OR = 0.86; 0.75; 0.98), surgery (OR = 0.52; 0.42; 0.64), blood transfusion (OR = 0.81; 0.75; 0.87), units of blood transfusion (MD = -4.30; -6.24; -2.36) and shorter LOS (MD = -1.70; -1.70; -1.70 days). Conclusion In contradistinction to observational studies, data from RCTs do not support a role for early colonoscopy in the routine management of acute LGIB with regards to the most important clinical outcomes. Further research is needed to better identify patients with high-risk LGIB who may benefit from early colonoscopy.