Rebleeding Risk of Acute Hemorrhagic Rectal Ulcer: A Multicenter Retrospective Study.

Objective Acute hemorrhagic rectal ulcer (AHRU) is characterized by sudden, painless, and massive bleeding from rectal ulcers. To date, few studies have analyzed the risk factors for AHRU rebleeding. In this study, we clarified the risk factors of rebleeding after initial hemostasis of AHRU through a multicenter study. Methods A total of 149 patients diagnosed with AHRU between January 2015 and May 2020 at 3 medical centers were enrolled. We retrospectively investigated the following factors: age, sex, body mass index (BMI), performance status (PS), Charlson comorbidity index (CCI), comorbidities, medications, laboratory examinations, endoscopic findings, view of the entire rectum on endoscopy, hemostasis method, blood transfusion history, shock, instructions for posture change after initial hemostasis, and clinical course. Results Rebleeding was observed in 35 (23%) of 149 patients. A multivariate analysis showed that significant factors for rebleeding were PS 4 [odds ratio (OR), 5.23; 95% confidence interval (CI)], 1.97-13.9; p=0.001], a blood transfusion history (OR, 3.66; 95% CI, 1.41-9.51; p=0.008), low an estimated glomerular filtration rate (eGFR) levels (OR, 0.98; 95% CI, 0.97-0.99; p=0.001), poor view of the whole rectum on endoscopy (OR, 0.33; 95% CI, 0.12-0.90; p=0.030), and use of monopolar hemostatic forceps (OR, 4.89; 95% CI, 1.37-17.4; p=0.014). Conclusion Factors associated with rebleeding of AHRU were a poor PS (PS4), blood transfusion, a low eGFR, poor view of the whole rectum on endoscopy, and the use of monopolar hemostatic forceps.

Multicenter prospective randomized controlled clinical trial comparing the pocket-creation method with and without single-clip traction of colonic endoscopic submucosal dissection.

BACKGROUND: The pocket-creation method (PCM) was developed to overcome the technical difficulties of endoscopic submucosal dissection (ESD), although opening the pocket remains challenging. We developed a novel technique of PCM with single-clip traction (PCM-CT), which uses a reopenable clip as a traction device to maintain stability during the procedure. No prospective study has compared the efficacy of PCM-CT and PCM. This study aimed to investigate the effectiveness of PCM-CT vs. PCM in a randomized controlled trial. METHODS: This randomized controlled clinical trial was conducted at four Japanese institutions. Patients with superficial colorectal neoplastic lesions were included following Japanese guidelines for colorectal cancer. Seven moderately experienced endoscopists performed the ESD procedures using either PCM-CT or PCM. RESULTS: 100 patients were enrolled in the study. Compared with PCM, PCM-CT achieved significantly faster mean (SD) dissection speed (21.4 [10.8] vs. 27.0 [14.5] mm2/min [95%CI 0.5 to 10.7], P = 0.03), and reduced the mean procedure time (81.8 [57.9] vs. 64.8 [47.6] minutes [95%CI -38.2 to 4.3], P = 0.12) and pocket-opening time (37.8 [33.0] vs. 30.0 [28.9] minutes [95%CI -20.2 to 4.6], P = 0.22). En bloc and R0 resection rates were not significantly different between the two groups (100% vs. 100%, P >0.99; 100% vs. 96%, P = 0.50, respectively). No significant differences were observed in adverse events between the two groups. CONCLUSION: ESD facilitated by the novel PCM-CT method appeared to be significantly faster than PCM. Both methods achieved high R0 resection rates.

An Analysis of Delayed Bleeding in Cases of Colorectal Endoscopic Submucosal Dissection Due to Types of Direct Oral Anticoagulants in Japan.

BACKGROUND & AIMS: Reported rates of delayed bleeding (DB) after endoscopic resection using direct oral anticoagulants (DOACs) are high and heterogeneous. This large-scale multicenter study analyzed cases of DB after colorectal endoscopic submucosal dissection related to various types of DOACs in Japan (the ABCD-J study) with those associated with warfarin. METHODS: We retrospectively reviewed 1019 lesions in patients treated with DOACs and 459 lesions in patients treated with warfarin among 34,455 endoscopic submucosal dissection cases from 47 Japanese institutions between 2012 and 2021. The DB rate (DBR) with each DOAC was compared with that with warfarin. Risk factors for DB in patients treated with DOACs or warfarin were also investigated. RESULTS: The mean tumor sizes in the DOAC and warfarin groups were 29.6 ± 14.0 and 30.3 ± 16.4 mm, respectively. In the DOAC group, the DBR with dabigatran (18.26%) was significantly higher than that with apixaban (10.08%, P = .029), edoxaban (7.73%, P = .001), and rivaroxaban (7.21%, P < .001). Only rivaroxaban showed a significantly lower DBR than warfarin (11.76%, P = .033). In the multivariate analysis, heparin bridging therapy (odds ratio [OR], 2.18; 95% confidence interval [CI], 1.27-3.73, P = .005), rectal location (2.01, 1.28-3.16, P = .002), and procedure time ≥55 minutes (2.43, 1.49-3.95, P < .001) were significant risk factors for DB in the DOAC group. The DB risk in the DOAC group (OR, (95% CI)) was 2.13 (1.30-3.50) and 4.53 (2.52-8.15) for 1 and 2 significant risk factors, respectively. CONCLUSIONS: Dabigatran was associated with a higher DBR than other DOACs, and only rivaroxaban was associated with a significantly lower DBR than warfarin.

Risk Factors and Predictive Biomarkers for Anastomotic Leakage after Colorectal Cancer Surgery with the Double Stapling Technique.

Objectives: Anastomotic leakage (AL) is a serious complication associated with morbidity, mortality, and poor prognosis. This study aimed to identify the risk factors and predictive biomarkers for AL after colorectal surgery with double stapling technique (DST) anastomosis. Methods: We retrospectively analyzed 331 patients who underwent elective colorectal cancer surgery with DST anastomosis between April 2012 and July 2021. Patient-, tumor-, and surgery-related variables were examined using univariate and multivariate analyses to identify the risk factors for AL. Postoperative inflammatory biomarkers were also analyzed to identify the predictive factors for AL. Results: AL occurred in 28 (8.5%) patients. In multivariate analysis, male sex, a history of diabetes mellitus and high ligation of inferior mesenteric artery (IMA) were significant risk factors for AL. Serum C-reactive protein (CRP) levels on postoperative day (POD) 3 and 7 were significantly correlated with AL (OR; 95% CI, 1.134; 1.044-1.232, p = 0.003, and 1.154; 1.036-1.286, p = 0.009, respectively). The cut-off value of CRP on POD 3 was 10.91 mg/dL (sensitivity 0.714, specificity 0.835, positive predictive value [PPV] 0.290, and negative predictive value [NPV] 0.969). The cut-off value of CRP on POD 7 was 4.58 mg/dL (sensitivity 0.821, specificity 0.872, PPV 0.377, and NPV 0.981). Conclusions: Male sex, a history of diabetes mellitus and high ligation of IMA were risk factors for AL in colorectal cancer surgery with DST anastomosis. The predictive biomarkers for cases without AL were CRP levels on POD 3 and 7.

Underwater endoscopic submucosal dissection for colorectal tumors decreases the incidence of post-electrocoagulation syndrome.

BACKGROUND AND AIMS: Underwater endoscopic submucosal dissection (U-ESD) is a recently developed procedure that has the potential to prevent post-ESD coagulation syndrome (PECS) owing to its heat-sink effect. We aimed to clarify whether U-ESD decreases the incidence of PECS compared with conventional ESD (C-ESD). METHODS: A total of 205 patients who underwent colorectal ESD (C-ESD: 125; U-ESD: 80) were analyzed. Propensity score matching analysis was performed to adjust for patient backgrounds. Ten C-ESD and two U-ESD patients with muscle damage or perforation during ESD were excluded when comparing PECS. The primary outcome was to compare the incidence of PECS between the U-ESD and C-ESD groups (54 matched pairs). Secondary outcomes were to compare procedural outcomes between the C-ESD and U-ESD groups (62 matched pairs). RESULTS: Among the 78 patients who underwent U-ESD, PECS occurred in only one patient (1.3%). Adjusted comparisons between the U-ESD and C-ESD groups demonstrated a significantly lower incidence of PECS in the U-ESD group (0% vs 11.1%; P = 0.027). Median dissection speed was significantly faster in the U-ESD than in the C-ESD group (10.9 mm2 /min vs 6.9 mm2 /min; P < 0.001). En bloc and complete resection rates were 100% in the U-ESD group. Although perforation and delayed bleeding occurred in one patient each (1.6%) as adverse events in the U-ESD group, there were no differences compared with the C-ESD group. CONCLUSIONS: Our study demonstrates that U-ESD effectively decreases the incidence of PECS and is a faster and safer method for colorectal ESD.

Visibility of early gastric cancers by texture and color enhancement imaging using a high-definition ultrathin transnasal endoscope.

We evaluated whether texture and color enhancement imaging (TXI) using a high-definition ultrathin transnasal endoscope (UTE) improves the visibility of early gastric cancer (EGC) compared with white-light imaging (WLI). This study included 31 EGCs observed by TXI mode 2 using a high-definition UTE prior to endoscopic submucosal dissection. The first outcome was to compare the color differences based on Commission Internationale de l'Eclairage L*a*b* color space between EGCs and the surrounding mucosa by WLI and TXI using the UTE (objective appearance of EGC). The second outcome was to assess the visibility of EGCs by WLI and TXI using the UTE in an image evaluation test performed on 10 endoscopists (subjective appearance of EGC). Color differences between EGCs and non-neoplastic mucosa were significantly higher in TXI than in WLI in all EGCs (TXI: 16.0 ± 10.1 vs. WLI: 10.2 ± 5.5 [mean ± standard deviation], P < 0.001). Median visibility scores evaluated by 10 endoscopists using TXI were significantly higher than those evaluated using WLI (TXI: 4 [interquartile range, 4-4] vs. WLI: 4 [interquartile range, 3-4], P < 0.001). TXI using high-definition UTE improved both objective and subjective visibility of EGCs compared with WLI.

Computer-aided diagnosis of early-stage colorectal cancer using nonmagnified endoscopic white-light images (with videos).

BACKGROUND AND AIMS: Differentiation of colorectal cancers (CRCs) with deep submucosal invasion (T1b) from CRCs with superficial invasion (T1a) or no invasion (Tis) is not straightforward. This study aimed to develop a computer-aided diagnosis (CADx) system to establish the diagnosis of early-stage cancers using nonmagnified endoscopic white-light images alone. METHODS: From 5108 images, 1513 lesions (Tis, 1074; T1a, 145; T1b, 294) were collected from 1470 patients at 10 academic hospitals and assigned to training and testing datasets (3:1). The ResNet-50 network was used as the backbone to extract features from images. Oversampling and focal loss were used to compensate class imbalance of the invasive stage. Diagnostic performance was assessed using the testing dataset including 403 CRCs with 1392 images. Two experts and 2 trainees read the identical testing dataset. RESULTS: At a 90% cutoff for the per-lesion score, CADx showed the highest specificity of 94.4% (95% confidence interval [CI], 91.3-96.6), with 59.8% (95% CI, 48.3-70.4) sensitivity and 87.3% (95% CI, 83.7-90.4) accuracy. The area under the characteristic curve was 85.1% (95% CI, 79.9-90.4) for CADx, 88.2% (95% CI, 83.7-92.8) for expert 1, 85.9% (95% CI, 80.9-90.9) for expert 2, 77.0% (95% CI, 71.5-82.4) for trainee 1 (vs CADx; P = .0076), and 66.2% (95% CI, 60.6-71.9) for trainee 2 (P < .0001). The function was also confirmed on 9 short videos. CONCLUSIONS: A CADx system developed with endoscopic white-light images showed excellent per-lesion specificity and accuracy for T1b lesion diagnosis, equivalent to experts and superior to trainees. (Clinical trial registration number: UMIN000037053.).

Targeted Metabolomic Profiling of Plasma Samples in Gastric Cancer by Liquid Chromatography-Mass Spectrometry.

INTRODUCTION: As the high mortality rate of gastric cancer (GC) is due to delayed diagnosis, early detection is vital for improved patient outcomes. Metabolic deregulation plays an important role in GC. Although various metabolite-level biomarkers for early detection have been assessed, there is still no unified early detection method. We conducted a plasma metabolome study to assess metabolites that may distinguish GC samples from non-GC samples. METHODS: Blood samples were collected from 72 GC patients and 29 control participants (non-GC group) at the Tokyo Medical University Hospital between March 2020 and November 2020. Hydrophilic metabolites were identified and quantified using liquid chromatography-time-of-flight mass spectrometry. Differences in metabolite concentrations between the GC and non-GC groups were evaluated using the Mann-Whitney test. The discrimination ability of each metabolite was evaluated by the area under the receiver operating characteristic curve. A radial basis function (RBF) kernel-based support vector machine (SVM) model was developed to assess the discrimination ability of multiple metabolites. The selection of variables used for the SVM utilized a step-wise regression method. RESULTS: Of the 96 quantified metabolites, 8 were significantly different between the GC and non-GC groups. Of these, N1-acetylspermine, succinate, and histidine were used in the RBF-SVM model to discriminate GC samples from non-GC samples. The area under the curve (AUC) of the RBF-SVM model was higher (0.915; 95% CI: 0.865-0.965, p < 0.0001), indicating good performance of the RBF-SVM model. The application of this RBF-SVM to the validation dataset resulted from the AUC of the RBF-SVM model was (0.885; 95% CI: 0.797-0.973, p < 0.0001), indicating the good performance of the RBF-SVM model. The sensitivity of the RBF-SVM model was better (69.0%) than those of the common tumor markers carcinoembryonic antigen (CEA) (10.5%) and carbohydrate antigen 19-9 (CA19-9) (2.86%). The RBF-SVM showed a low correlation with CEA and CA19-9, indicating its independence. CONCLUSION: We analyzed plasma metabolomics, and a combination of the quantified metabolites showed high sensitivity for the detection of GC. The independence of the RBF-SVM from tumor markers suggested that their complementary use would be helpful for GC screening.

Short-term outcomes of patients undergoing endoscopic submucosal dissection for colorectal lesions.

Objectives: Endoscopic submucosal dissection (ESD) of colorectal lesions was invented in Japan, but postoperative management including hospital stay has not been reconsidered due to the Japanese insurance system. To explore appropriate postoperative management after colorectal ESD, we reviewed short-term outcomes after ESD in non-selected consecutive patients. Methods: Patients who underwent colorectal ESD from April 2013 to September 2020 in one institution were reviewed. The primary outcome measure was the occurrence of adverse events stratified by the Clavien-Dindo classification with five grades. A logistic regression model with the Firth procedure was applied to investigate predictors of severe (grade III or greater) adverse events. Results: A total of 330 patients (female 40%, male 60%; median 72 years; IQR 65-80 years) with colorectal lesions (median 30 mm, IQR 23-40 mm; colon 77%, rectum 23%; serrated lesion 4%, adenoma 47%, mucosal cancer 30%, invasive cancer 18%) was evaluated. The en bloc resection rate was 97%. The median dissection time was 58 min (IQR: 38-86). Intraprocedural perforation occurred in 3%, all successfully treated by endoscopic clipping. No delayed perforations occurred. Postprocedural bleeding occurred in 3% on days 1-10 (median day 2); all were controlled endoscopically. Severe adverse events included only delayed bleeding. In analyzing severe adverse events in a multivariate logistic regression model with the Firth procedure, antithrombotic agent use (p = 0.016) and rectal lesions (p = 0.0010) were both significant predictors. Conclusions: No serious adverse events occurred in this series. Four days of hospitalization may be too long for the majority of patients after ESD.

Prediction of depth of invasion and lymph node metastasis in superficial pharyngeal cancer by magnifying endoscopy using the Japan Esophageal Society classification.

Backgrounds: The pharynx has no muscularis mucosae, so it is unclear whether diagnostic techniques used for the esophagus can be applied to the pharynx. This study investigated the usefulness of magnifying endoscopy with narrowband imaging using the Japan Esophageal Society (JES) classification for predicting the depth of invasion and lymph node metastasis (LNM) in pharyngeal cancer. Methods: A total of 123 superficial pharyngeal carcinoma lesions that had been observed preoperatively with magnifying endoscopy with narrowband imaging between January 2014 and June 2021 were analyzed. Predictors of subepithelial invasion (SEP) and LNM were sought based on endoscopic findings, including microvascular morphology, using the JES classification. Results: The lesions were divided into carcinoma in situ (n = 41) and SEP (n = 82). Multivariate analysis identified B2-B3 vessels (odds ratio [OR] 6.54, 95% confidence interval [CI] 1.74-24.61, p = 0.005) and a middle/large avascular area (OR 4.15, 95% CI 1.18-14.62, p = 0.027) as independent predictors of SEP. Significant predictors of LNM were protruding type, B2-B3 vessels, middle/large avascular area, SEP, venous invasion, lymphatic invasion, and tumor thickness > 1000 µm. Median tumor thickness increased significantly in the order of B1 < B2 < B3 vessels (B1, 305 µm; B2, 1045 µm; B3, 4043 µm; p < 0.001). The LNM rates for B1, B2, and B3 vessels were 1.6% (1/63), 4.8% (2/42), and 55.6% (10/18), respectively (p < 0.001). Conclusions: Magnifying endoscopy with narrowband imaging using the JES classification could predict the depth of invasion in superficial pharyngeal carcinoma. The JES classification may contribute to the prediction of LNM, suggesting that it could serve as an alternative to tumor thickness.

Randomized controlled trial comparing conventional and traction endoscopic submucosal dissection for early colon tumor (CONNECT-C trial).

OBJECTIVES: Endoscopic submucosal dissection (ESD) is a widely used treatment for early gastrointestinal cancer. However, colon ESD remains challenging. Previous studies on colon ESD using the traction method used a small sample, single-center design, providing insufficient evidence of this procedure's efficacy. We thus aimed to investigate the efficacy and safety of the traction method in colon ESD in this multicenter randomized trial. METHODS: We conducted a prospective, multicenter, randomized, two-arm controlled trial at 10 facilities in Japan. A 1:1 allocation was conducted for the conventional ESD (C-ESD) and traction ESD (T-ESD) groups. The primary end-point was ESD procedure time. RESULTS: We included 128 C-ESD and 123 T-ESD cases from April 2020 to August 2021. The median procedure times for C-ESD and T-ESD were 61 (40-100) and 53 (40-76) min (P = 0.18), respectively, and no significant differences were observed between the groups. Subgroup analysis showed that the median procedure times for patients with a lesion diameter of ≥30 mm in the C-ESD and T-ESD groups were 89 (57-80) and 69 (50-104) min (P = 0.05), respectively, and for nonexpert operators were 81 (62-120) and 64 (52-109) min (P = 0.07), respectively. CONCLUSIONS: The traction method did not contribute to a significantly shortened ESD procedure time. However, this method may be useful when the tumor diameter is large or if the procedure is conducted by nonexpert endoscopists.

Gauze extension method for specimens resected by endoscopic submucosal dissection.

Video 1The gauze extension method for resected specimens.

Computer-aided diagnosis of serrated colorectal lesions using non-magnified white-light endoscopic images.

PURPOSE: Computer-aided diagnosis systems for polyp characterization are commercially available but cannot recognize subtypes of sessile lesions. This study aimed to develop a computer-aided diagnosis system to characterize polyps using non-magnified white-light endoscopic images. METHODS: A total of 2249 non-magnified white-light images from 1030 lesions including 534 tubular adenomas, 225 sessile serrated adenoma/polyps, and 271 hyperplastic polyps in the proximal colon were consecutively extracted from an image library and divided into training and testing datasets (4:1), based on the date of colonoscopy. Using ResNet-50 networks, we developed a classifier (1) to differentiate adenomas from serrated lesions, and another classifier (2) to differentiate sessile serrated adenoma/polyps from hyperplastic polyps. Diagnostic performance was assessed using the testing dataset. The computer-aided diagnosis system generated a probability score for each image, and a probability score for each lesion was calculated as the weighted mean with a log10-transformation. Two experts (E1, E2) read the identical testing dataset with a probability score. RESULTS: The area under the curve of classifier (1) for adenomas was equivalent to E1 and superior to E2 (classifier 86%, E1 86%, E2 69%; classifier vs. E2, p < 0.001). In contrast, the area under the curve of classifier (2) for sessile serrated adenoma/polyps was inferior to both experts (classifier 55%, E1 68%, E2 79%; classifier vs. E2, p < 0.001). CONCLUSION: The classifier (1) developed using white-light images alone compares favorably with experts in differentiating adenomas from serrated lesions. However, the classifier (2) to identify sessile serrated adenoma/polyps is inferior to experts.

Rectal cancer eradication by proton beam therapy complicated by radiation proctitis: a case report.

A 74-year-old woman presented to her local physician with hematochezia. Colonoscopy showed a locally advanced 30 mm cancer adjacent to the anus. She refused abdominoperineal resection because of the necessity for a permanent stoma and decided to receive proton beam therapy (70.4 Gy equivalent) as an alternative treatment in another hospital. After proton beam therapy, the rectal cancer was eradicated at colonoscopy, and she was referred for surveillance. One year later, she developed frequent hematochezia. Colonoscopy revealed dilated vessels with oozing hemorrhage in the tumor scar. This was diagnosed as hemorrhagic radiation proctitis induced by proton beam therapy. Over 8 months, endoscopic hemostatic therapy was performed five times using argon plasma coagulation for refractory hemorrhagic disease. The patient's hemoglobin level dropped to as low as 4.5 g/dl requiring blood transfusion. Thereafter, the radiation proctitis gradually improved and there is no evidence of recurrent tumor for over 10 years. To the best of our knowledge, there are no previous reports of proton beam therapy eradication of locally advanced rectal cancer. Clinicians should be aware that radiation-induced proctitis with refractory hemorrhage could develop.

Endoscopic submucosal dissection using traction by a spring-and-loop with clip for a laterally spreading tumor in the inferior aspect of the cecum: a nonreferral center experience.

Video 1Endoscopic submucosal dissection using traction by a spring-and-loop with clip for a laterally spreading tumor in the inferior aspect of the cecum: a nonreferral center experience.

Validation of the BEST-J score, a prediction model for bleeding after endoscopic submucosal dissection for early gastric cancer: a multicenter retrospective observational study.

BACKGROUND: A new scoring system, the BEST-J score, using ten risk factors to assign cases to different post-endoscopic submucosal dissection (ESD) risk groups for bleeding, has been shown to be accurate for risk stratification. We first aimed to validate the BEST-J score at four hospitals not specialized in performing ESD and then aimed to identify other risk factors for post-ESD bleeding. METHODS: We evaluated the incidence of post-ESD bleeding in 791 cases of early gastric cancer (EGC) between October 2013 and December 2020 as a retrospective, multi-center observational study conducted at four hospitals. Multivariate logistic regression models to examine the effect of independent variables on post-ESD bleeding firstly included ten possible factors raised by the BEST-J score and secondly included statistically significant (p < 0.01) in univariate analysis. The prediction accuracy of the model was evaluated by receiver-operating characteristic analysis and the areas under the curve (AUC). RESULTS: The incidence of post-ESD bleeding was 4.8% (38/791, 95% confidence interval [CI] 3.4-6.5%). On multivariate analysis, the risk factors were P2Y12 receptor antagonist (odds ratio [OR]: 5.870, 95% CI 1.624-21.219), warfarin (8.382, 1.658-42.322), direct oral anticoagulant (DOAC) (8.980, 1.603-50.322), and tumor location in lower third of stomach (2.151, 1.012-4.571), respectively. When we categorized cases into low-risk by BEST-J score, intermediate-risk, high-risk, and very high-risk groups, the bleeding rates were 2.8%, 7.3%, 12.8%, and 19.0%, respectively. The AUC for our cohort was 0.713 (95% CI 0.625-0.802) for the BEST-J score. In the multivariate analysis in our cohort, the risks were age, body mass index, P2Y12 receptor antagonist, warfarin, DOAC, respectively. DISCUSSION: The BEST-J score is equally accurate in risk stratification of patients with EGC for post-ESD bleeding at non-specialized facilities for ESD as in specialized hospitals. BMI and age may be helpful additional risk factors at hospitals not specialized.

Risk of Delayed Bleeding after Cold Snare Polypectomy in Patients with Antithrombotic Therapy.

BACKGROUND: Cold snare polypectomy is being increasingly adopted; however, there are few reports of cold snare polypectomy regarding antithrombotic therapy. AIMS: This study aimed to investigate the real-world safety of cold snare polypectomy during antithrombotic therapy. METHODS: We collected data from consecutive patients undergoing cold snare polypectomy in a single hospital between 2013 and 2017. Indications for cold snare polypectomy were any ≤ 10 mm polyp. The primary outcome was delayed bleeding. We compared rates of delayed bleeding between patients with and without antithrombotic therapy and analyzed risk factors for delayed bleeding using binary logistic regression model with firth procedure. RESULTS: In 2152 patients (mean age 67.6 years; male 1411), 4433 colorectal polyps (mean diameter 5.0 mm) underwent cold snare polypectomy. Clipping during the procedure was performed for 5.8%. Delayed bleeding occurred in 0.51% (11/2152) of patients and 0.25% (11/4433) of polyps, but no major delayed bleeding occurred. A total of 244 (11%) patients received antithrombotic therapy. Patients on antithrombotic therapy were older (p < 0.001), more likely male (p < 0.001) and had cold snare polypectomy in the proximal colon (p = 0.011). The rate of delayed bleeding was higher in patients on antithrombotic therapy (1.64% vs. non-antithrombotic therapy 0.37%, p = 0.009). Larger polyp size (> 5 mm), use of clips, and antithrombotic therapy were significant risk factors for delayed bleeding. There was no clear association between specific antithrombotic agents and delayed bleeding. CONCLUSIONS: Delayed bleeding after cold snare polypectomy was rare even in patients with antithrombotic therapy, and no major delayed bleeding occurred.