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.

This is a multicenter, prospective, single-blind, randomized controlled, non-inferiority study. The study includes the following steps:

Step 1: Participants will be enrolled based on predefined criteria, and demographic data, fasting water duration, accompanying symptoms, smoking history, alcohol consumption history, antithrombotic drug usage, previous history of lower gastrointestinal bleeding, Charlson comorbidity index, vital signs at admission, and laboratory results at admission will be collected.

Step 2: All participants will undergo stratified block randomization, and based on the randomization results, participants will receive bowel preparation using either PEG or enema. Subsequently, all participants will undergo urgent colonoscopy within 48 hours from admission.

Step 3: Follow-up records will be conducted at the following time points:

1. Before colonoscopy:

   * Record the specific method and dosage of actual bowel preparation.
   * Record changes in vital signs, symptoms, and signs before and after bowel preparation, as well as occurrences of adverse events.
   * Conduct a satisfaction survey of bowel preparation.
2. During colonoscopy:

   - Record patient pain scores, Boston bowel preparation scores, cecal intubation time, lesion detection time, total procedure time, maximum insertion depth, observation of active bleeding, endoscopic diagnosis, endoscopic hemostasis, and perforation.
3. After colonoscopy:

   * Record postoperative adverse events, need for repeat endoscopy, transfusion, intervention or surgery, and final discharge diagnosis.

Eligibility Criteria:
Inclusion Criteria:

Patients presenting with hematochezia who were admitted to our hospitals were eligible for the study. Patients were included if they met the following criteria:

1. Had the last bloody bowel movement within 24 hours of presentation;
2. Aged 18 years or over
3. Had indications for clinical colonoscopy

Exclusion Criteria:

1. Known or suspected upper gastrointestinal bleeding meeting any of the following criteria:

   A. Presence of hematemesis or black vomiting. B. Bloody or coffee nasogastric aspirate. C. Endoscopic evidence of acute upper gastrointestinal bleeding, such as gastric or duodenal ulcer bleeding, esophagogastric variceal bleeding, etc.
2. Previous colonoscopy has been performed at an external institution with a confirmed diagnosis.
3. Presence of primary or secondary coagulation disorders.
4. History of bowel diversion surgery (including partial colon resection).
5. Hemodynamic instability persists after fluid resuscitation (shock index greater than 1).
6. Interventional treatment has been performed and hemostasis has been successfully achieved.
7. Requires transfer to an intensive care unit due to the severity of the condition.
8. Unable to comply with oral polyethylene glycol administration or enema procedures.
9. Known or suspected relative contraindications to colonoscopy, such as toxic megacolon, acute intestinal obstruction, acute myocardial infarction, heart failure, severe liver failure, and end-stage renal disease.
10. Pregnant or lactating women.