Oral PEG vs. Enema in Urgent Colonoscopy for ALGIB

Enema Group (Experimental Group): Enema is administered using either normal saline or 1% soapy water for cleansing until the effluent is clear of fecal debris, or until a total volume of 3000 ml of enema solution has been administered. The enema should be initiated 4-6 hours before colonoscopy, with the dosage and frequency of incremental enemas determined based on the patient's tolerance. The final enema administration should be completed no later than 10 minutes before the scheduled colonoscopy.

Oral PEG Group (Control Group): Following the administration protocol recommended by the Chinese expert consensus for PEG, a 3 L PEG regimen is employed. The regimen involves segmented intake, with 1 L taken 10-12 hours before the intestinal examination and an additional 2 L taken 4-6 hours before the examination on the day of the procedure.