Timing of colonoscopy in acute lower GI bleeding: a multicenter retrospective cohort study

Post written by Yasutoshi Shiratori, MD, MPH, PhD, from the Department of Gastroenterology, St. Luke’s International University, and Naoki Ishii, MD, MPH, PhD, from the Department of Gastroenterology, Tokyo Shinagawa Hospital, Tokyo, Japan.


Acute lower GI bleeding (ALGIB) is a primary cause of hospital admissions from the emergency department and is associated with a 3.4% mortality.

However, the optimal timeframe for colonoscopy in patients with ALGIB and the benefit derived from early colonoscopy (≤24 hours) remain controversial.

We evaluated the effects of colonoscopy timing on the clinical outcomes of patients with ALGIB. We also investigated the interaction between colonoscopy timing and baseline characteristics for the primary outcome (30-day rebleeding) to identify which patients with ALGIB benefited from early colonoscopy.


We felt it was important to conduct this study because, although guidelines for the treatment of ALGIB have been published in the United States, Europe, and Asia, consensus on the ideal time to perform colonoscopy is lacking.

In addition, a systematic review reported a difference in the effectiveness of early colonoscopy between randomized controlled trials (RCTs) and observational studies. This discrepancy could be related to the lower proportion of hemodynamically unstable patients in RCTs (6.0%-47.2% in observational studies vs .02%-5.1% in RCTs).

Furthermore, no comparative studies have been performed on the nonearly (>24 hours) colonoscopy group. Evidence of colonoscopy after 24 hours helps with the management of ALGIB patients on weekends and holidays.

Therefore, we performed a multicenter study using large and detailed patient data from the CODE-BLUE-J study.

Our study makes a significant contribution to the literature because this cohort was the largest study population with ALGIB to undergo analysis for the effect of confounding background factors on colonoscopy timing such as patients’ vitals, hematological data, comorbidities, and medications.

Evaluating colonoscopy timing (≤24 hours, 24-48 hours, and >48 hours) using inverse probability of treatment weighting, we demonstrated that early colonoscopy improved stigmata of recent hemorrhage identification and shortened length of stay.

However, early colonoscopy was associated with a higher 30-day rebleeding rate and did not improve mortality and interventional radiology or surgery requirement. In the subgroup analyses based on shock index and performance status (PS) in which the interaction was observed, early colonoscopy was beneficial for those with a shock index ≥1 or PS ≥3.

Therefore, most ALGIB patients do not need to receive colonoscopy immediately. Rather, vitals and PS could be an indication of the requirement for early colonoscopy. These may directly impact health and patient outcomes. Additional RCTs are warranted to clarify these findings.


Study flowchart.

Read the full article online.

The information presented in Endoscopedia reflects the opinions of the authors and does not represent the position of the American Society for Gastrointestinal Endoscopy (ASGE). ASGE expressly disclaims any warranties or guarantees, expressed or implied, and is not liable for damages of any kind in connection with the material, information, or procedures set forth.

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