INTRODUCTION: The bleeding source of hematochezia is unknown without performing colonoscopy. We sought to identify whether colonoscopy is a risk-stratifying tool to identify etiology and predict outcomes and whether presenting symptoms can differentiate the etiologies in patients with hematochezia. METHODS: This multicenter retrospective cohort study conducted at 49 hospitals across Japan analyzed 10,342 patients admitted for outpatient-onset acute hematochezia. RESULTS: Patients were mostly elderly population, and 29.5% had hemodynamic instability. Computed tomography was performed in 69.1% and colonoscopy in 87.7%. Diagnostic yield of colonoscopy reached 94.9%, most frequently diverticular bleeding. Thirty-day rebleeding rates were significantly higher with diverticulosis and small bowel bleeding than with other etiologies. In-hospital mortality was significantly higher with angioectasia, malignancy, rectal ulcer, and upper gastrointestinal bleeding. Colonoscopic treatment rates were significantly higher with diverticulosis, radiation colitis, angioectasia, rectal ulcer, and postendoscopy bleeding. More interventional radiology procedures were needed for diverticulosis and small bowel bleeding. Etiologies with favorable outcomes and low procedure rates were ischemic colitis and infectious colitis. Higher rates of painless hematochezia at presentation were significantly associated with multiple diseases, such as rectal ulcer, hemorrhoids, angioectasia, radiation colitis, and diverticulosis. The same was true in cases of hematochezia with diarrhea, fever, and hemodynamic instability. DISCUSSION: This nationwide data set of acute hematochezia highlights the importance of colonoscopy in accurately detecting bleeding etiologies that stratify patients at high or low risk of adverse outcomes and those who will likely require more procedures. Predicting different bleeding etiologies based on initial presentation would be challenging.

There is the East-West paradox in prevalence and phenotype of colonic diverticula, but colonic diverticular bleeding (CDB) is the most common cause of acute lower gastrointestinal bleeding worldwide. Death from CDB can occur in elderly patients with multiple comorbidities, thus the management of CDB is clinically pivotal amid the aging populations in the East and West. Colonoscopy is the key modality for managing the condition appropriately; however, conventional endoscopic hemostasis by thermal coagulation and clipping cannot achieve the expected results of preventing early rebleeding and conversion to intensive intervention by surgery or transcatheter arterial embolization. Ligation therapy by endoscopic band ligation or endoscopic detachable snare ligation has emerged recently to enable more effective hemostasis for CDB, with an early rebleeding rate of approximately 10% and very rare conversion to intensive intervention. Ligation therapy might in turn reduce long-term rebleeding rates by eliminating the target diverticulum itself. Adverse events have been reported with ligation therapy including diverticulitis of the ascending colon in less than 1% of cases and perforation of the sigmoid colon in a few cases, thus more data are necessary to verify the safety of ligation therapy. Endoscopic hemostasis is indicated only for diverticulum with stigmata of recent hemorrhage (SRH), but the detection rates of SRH are relatively low. Therefore, efforts to increase detection are also key for improving CDB management. Urgent colonoscopy and triage by early contrastenhanced computed tomography may be candidates to increase detection but further data are necessary in order to make a conclusion. Digestive Endoscopy 2020; 32: 240-250 Control of colonic diverticular bleeding 241 Digestive Endoscopy 2020; 32: 240-250 Control of colonic diverticular bleeding 247 Digestive Endoscopy 2020; 32: 240-250 Control of colonic diverticular bleeding 249

BackgroundThe value of endoscopy for acute lower GI bleeding (ALGIB) remains unclear, given few large cohort studies. We aim to provide detailed clinical data for ALGIB management and to identify patients at risk for adverse outcomes based on endoscopic diagnosis.MethodsWe conducted a multicenter, retrospective cohort study, named CODE BLUE J-Study, in 49 hospitals throughout Japan and studied 10,342 cases admitted for outpatient-onset of acute hematochezia.ResultsCases were mostly elderly, with 29.5% hemodynamic instability and 60.1% comorbidity. 69.1% and 87.7 % of cases underwent CT and colonoscopy, respectively. Diagnostic yield of colonoscopy reached 94.9%, revealing 48 etiologies, most frequently diverticular bleeding. During hospitalization, the endoscopic therapy rate was 32.7%, mostly using clipping and band ligation. IVR and surgery were infrequently performed, for 2.1% and 1.4%. In-hospital rebleeding and death occurred in 15.2% and 0.9%. Diverticular bleeding cases had higher rates of hemodynamic instability, rebleeding, endoscopic therapy, IVR, and transfusion, but lower rates of death and surgery than other etiologies. Small bowel bleeding cases had significantly higher rates of surgery, IVR, and transfusion than other etiologies. Malignancy or upper GIB cases had significantly higher rates of thromboembolism and death than other etiologies. Etiologies that have favorable outcomes were ischemic colitis, infectious colitis, and post-endoscopy bleeding.ConclusionsLarge-scale data of patients with acute hematochezia revealed high proportions of colonoscopy and CT, resulting in high endoscopic therapy rates. We highlight the importance of colonoscopy in detecting accurate bleeding etiologies that stratify patients at high or low risk of adverse outcomes.

Background and study aims: Prior studies have shown the effectiveness of endoscopic band ligation (EBL) and clipping for colonic diverticular hemorrhage (CDH) but have been small and conducted at single centers. Thus, we investigated which was the more effective and safe treatment in a multicenter long-term cohort study. Patients and methods: We reviewed data for 1,679 patients with CDH who were treated with EBL (n=638) or clipping (n=1,041) between January 2010 and December 2019 at 49 hospitals across Japan (CODE BLUE-J Study). Logistic regression analysis was used to compare outcomes between the two treatments. Results: In multivariate analysis, EBL compared with clipping was independently associated with reduced risk of early rebleeding (adjusted odds ratio [AOR] 0.46; p<0.001) and late rebleeding (AOR 0.62; p<0.001). These significantly lower rebleeding rates with EBL were evident regardless of active bleeding or early colonoscopy. No significant difference was found between the treatments in the rate of initial hemostasis or mortality. EBL compared with clipping independently reduced the risk of need for interventional radiology (IVR) (AOR 0.37; p=0.006) and prolonged length of hospital stay (LOS) (AOR 0.35; p<0.001), but not need for surgery. Diverticulitis developed in 1 patient (0.16%) following EBL and 2 patients (0.19%) following clipping. Perforation occurred in 2 patients (0.31%) following EBL and none following clipping. Conclusions: Analysis of our large endoscopy dataset suggests that EBL is an effective and safe endoscopic therapy for CDH offering the advantages of lower early and late rebleeding rates, reduced need for IVR, and shorter LOS.

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