Oral PEG vs. Enema in Urgent Colonoscopy for ALGIB

The main goal of this study is to assess whether the diagnostic efficacy of enema is non-inferior to that of oral polyethylene glycol (PEG) in acute lower gastrointestinal bleeding (ALGIB) patients requiring urgent colonoscopy. The secondary objectives include: 1) evaluating potential differences between the enema and oral PEG groups in terms of the difficulty and safety of colonoscopy, as well as exacerbation of bleeding; 2) conducting subgroup analyses to compare the effectiveness of the two bowel preparation methods in specific populations, exploring potential candidate groups for different bowel preparation strategies, and promoting individualized diagnosis and treatment for ALGIB.