Prognostic Factors for Severe-to-Fatal Post-Endoscopic Retrograde Cholangiopancreatography Pancreatitis: A Multicenter Prospective Cohort Study.

The prognostic factors associated with severe-to-fatal post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP) remain unclear despite the extensive number of studies on PEP. In total, 3739 ERCP patients with biliary disease with an intact papilla and indicated for ERCP were prospectively enrolled at 36 centers from April 2017 to March 2018. Those with acute pancreatitis diagnosed before ERCP, altered gastrointestinal anatomy, and an American Society of Anesthesiologists (ASA) physical status > 4 were excluded. Univariate and multivariate logistic regression analyses were performed on patient-related factors, operator-related factors, procedure-related factors, and preventive measures to identify potential prognostic factors for severe-to-fatal PEP. Multivariate analyses revealed pancreatic guidewire-assisted biliary cannulation (OR 13.59, 95% CI 4.21-43.83, p < 0.001), post-ERCP non-steroidal anti-inflammatory drug (NSAID) administration (OR 11.54, 95% CI 3.83-34.81, p < 0.001), and previous pancreatitis (OR 6.94, 95% CI 1.45-33.33, p = 0.015) as significant risk factors for severe-to-fatal PEP. Preventive measures included endoscopic biliary sphincterotomy (EST; OR 0.29, 95% CI, 0.11-0.79, p = 0.015) and prophylactic pancreatic stents (PPSs; OR 0.11, 95% CI, 0.01-0.87, p = 0.036). In biliary ERCP, pancreatic guidewire-assisted biliary cannulation, NSAID administration after ERCP, and previous pancreatitis were risk factors for severe-to-fatal PEP, whereas EST and PPS were significant preventive measures for severe-to-fatal PEP.

Delayed Perforation of Colorectal Endoscopic Submucosal Dissection Treated by Endoscopic Ultrasound-Guided Drainage.

We report a case of a 70-year-old male with delayed perforation in the cecum treated by endoscopic ultrasonography-guided drainage for a pelvic abscess. The lesion was a 50-mm laterally spreading tumor, and endoscopic submucosal dissection (ESD) was performed. No perforation was detected during the operation, and en bloc resection was achieved. He had fever and abdominal pain on postoperative day (POD) 2. Computed tomography (CT) revealed the intra-abdominal free air, leading to a diagnosis of delayed perforation after ESD. Vital signs were stable, the perforation was considered minor, and endoscopic closure was attempted. The colonoscopy under fluoroscopy showed no perforation in the ulcer and no leakage of the contrast medium. He was managed conservatively with antibiotics and nothing per os. Symptoms improved; however, a follow-up CT on POD 13 revealed a 65-mm pelvic abscess, and endoscopic ultrasound (EUS)-guided drainage was successfully performed. The follow-up CT on POD 23 showed the reduction of abscess, and the drainage tubes were removed. Emergent surgical treatment is crucial in delayed perforation because it has a poor prognosis, and reports of conservative therapy for colonic ESD with delayed perforation are few. The present case was managed with antibiotics and EUS-guided drainage. Thus, EUS-guided drainage can be a treatment option for delayed perforation after colorectal ESD, if the abscess is localized.

Severe biliary hemorrhage after metal stent placement into the bile duct.

Sugimoto and colleagues report a rare case of life-threatening biliary hemorrhage as a complication of stent placement into the bile duct in a patient undergoing chemotherapy. The report illustrates that, if a patient placed metal stent shows an unexplainable anemia, biliary hemorrhage should be considered even without extravasation or pseudoaneurysms.

Does endoscopic sphincterotomy contribute to the prevention of post-endoscopic retrograde cholangiopancreatography pancreatitis after endoscopic biliary stenting for malignant biliary obstruction? A multicenter prospective cohort study.

BACKGROUND: There is no consensus on the necessity of endoscopic sphincterotomy (ES) to prevent post-endoscopic retrograde cholangiopancreatography pancreatitis (PEP) after endoscopic stenting in patients with malignant biliary obstruction. We investigated the incidence of PEP after endoscopic biliary stenting for malignant biliary obstruction with or without ES in a multicenter prospective cohort study. METHODS: We enrolled 807 patients who underwent endoscopic biliary stenting for malignant biliary obstruction with a native papilla at 36 hospitals between April 2017 and March 2018. The incidence of PEP in patients with or without ES was compared for subgroups based on stent type, placement method, and patient background. Univariate and multivariate analysis was performed to investigate the incidence of PEP in all stenting patients. RESULTS: Plastic and metal stents (MS) were inserted in 598 and 209 patients, respectively. The incidence of PEP in patients with or without ES was 7.9% and 7.4%, respectively among all stenting patients. The incidences of PEP with or without ES in plastic stent insertion patients, patients with MS insertion, stent insertions across the papilla, stent insertions across the papilla in patients without main pancreatic duct obstruction, and fully covered MS insertions across the papilla were compared. There was no overall significant difference in the incidence of PEP between those with or without ES. Multivariate logistic regression analysis for the incidence of PEP in all stenting patients revealed obstruction of the main pancreatic duct at the pancreatic head and epinephrine spraying on the papilla were significant factors; there was no significant difference in the incidence of PEP between patients with or without ES. CONCLUSION: Endoscopic sphincterotomy may not contribute to the prevention of PEP after endoscopic biliary stenting for malignant biliary obstruction, even in cases of insertion with a fully covered MS across the papilla.

Medical radiation exposure during gastrointestinal enteral metallic stent placement: Post hoc analysis of the REX-GI study.

Background and Aim: Recently, the use of various endoscopic procedures performed under X-ray fluoroscopy guidance has increased. With the popularization of such procedures, diagnostic reference levels (DRLs) have been widely accepted as the global standard for various procedures with ionizing radiation. The Radiation Exposure from Gastrointestinal Fluoroscopic Procedures (REX-GI) study aimed to prospectively collect actual radiation exposure (RE) data and establish DRLs in gastrointestinal endoscopy units. In this post hoc analysis of the REX-GI study, we established DRLs for each disease site by analyzing cases of gastrointestinal enteral metallic stent placement. Methods: The REX-GI study was a multicenter, prospective observational study conducted to collect actual RE data during gastrointestinal enteral metallic stent placement. To establish DRL values for three disease sites, namely the esophagus, gastroduodenum, and colon, we examined fluoroscopy time (FT; min), number of X-ray images, air kerma at the patient entrance reference point (K a,r; mGy), and the air kerma-area product (P KA; Gy cm2) during enteral metallic stent placement. Results: Five-hundred and twenty-three stenting procedures were performed. The DRL values of FT (min) and the number of X-ray images for the esophagus/gastroduodenum/colon were 9/16/18 min and 9/15/11 min, respectively. Furthermore, the DRL values of K a,r and P KA for each disease site were 43.3/120/124 mGy and 10.3/36.6/48.4 Gy cm2, respectively. Among the procedures, esophageal stents were significantly associated with the lowest values (P < 0.001). Conclusion: The characteristics of RE vary according to disease site among gastrointestinal enteral metallic stent placements. Thus, it is desirable to set DRL values based on the disease site.

Effect of ice water injection toward the duodenal papilla for preventing post-ERCP pancreatitis: study protocol for a multicenter, single-blinded, randomized controlled trial (EUTOPIA study).

BACKGROUND: Endoscopic retrograde cholangiopancreatography (ERCP) is an essential procedure in the diagnosis and treatment of biliopancreatic diseases. The most common adverse event of ERCP is post-ERCP pancreatitis (PEP), which can sometimes be severe. Our previous study suggested that injecting ice water at the end of ERCP suppressed PEP, and we decided to investigate this effect in a multicenter randomized controlled trial. METHODS: This study is being conducted at eight hospitals in Japan starting in April 2022. Patients undergoing ERCP will be randomized to ice water group and control group. In the ice water group, 250 ml of ice water is injected toward the papilla at the end of ERCP. The next morning, a physical examination and blood tests are performed to evaluate for the development of pancreatitis. The goal is to have 440 cases in each group. DISCUSSION: The main cause of PEP is thought to be papilla edema. Cooling the papilla, as everyone naturally does at the time of a burn, is expected to prevent its inflammation and edema. Various methods to suppress PEP have been reported, but so far none of them are reliable. The method we have devised is very simple, easy, and safe. We hope that our study will change the world's ERCP common practice. TRIAL REGISTRATION: UMIN000047528. Registered 20 April 2022, https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000053209.

Carcinoma in situ of the perihilar bile duct diagnosed by peroral cholangioscopy.

It is rare for cholangiocarcinoma to be diagnosed as carcinoma in situ. Iwano and colleagues present a case in which stone formation in the hilar region contributed to the diagnosis. In such case, it is important to note minor changes on cholangiography and consider a detailed examination such as peroral cholangioscopy.

Comparison of 22-gauge standard and Franseen needles in EUS-guided tissue acquisition for diagnosing solid pancreatic lesions: a multicenter randomized controlled trial.

BACKGROUND AND AIMS: This large multicenter randomized controlled trial compared the diagnostic yields of 22-gauge standard and 22-gauge Franseen needles for EUS-guided tissue acquisition (EUS-TA) of solid pancreatic lesions. METHODS: Consecutive patients with solid pancreatic lesions were prospectively randomized to EUS-TA using standard or Franseen needles. Samples obtained with the first needle pass and with second and subsequent passes were evaluated separately. The primary endpoint was the rate of accuracy for diagnosis of malignancy. Other endpoints were technical success rate, sample cellularity, adverse events, diagnostic accuracy in patient subgroups, and the diagnostic accuracy and numbers of second and subsequent needle passes. RESULTS: Of 523 patients undergoing EUS-TA, 260 were randomized to using standard 22-gauge needles and 263 to 22-gauge Franseen needles. The technical success rate in each group was 99.6%, with similar adverse event rates in the standard (1.5%) and Franseen (.8%) needle groups. First-pass EUS-TA using the Franseen needle resulted in significantly greater diagnostic accuracy (84.0% vs 71.2%, P < .001) and sensitivity (82.4% vs 66.7%, P < .001) than first-pass EUS-TA using a standard needle and also resulted in superior diagnostic accuracy in patients requiring immunostaining. Second and subsequent EUS-TA using Franseen needles showed significantly greater accuracy (94.7% vs 90.0%, P = .049) and sensitivity (94.0% vs 88.6%, P = .047) and required fewer needle passes (1.81 vs 2.03, P = .008) than using standard needles. CONCLUSIONS: EUS-TA with the Franseen needle is superior to EUS-TA with a standard needle with respect to diagnostic accuracy per pass, particularly in patients who require immunostaining, and number of passes when using macroscopic on-site evaluation. (Clinical trial registration numbers: UMIN000030634 and jRCTs052180062.).

Cooling the papilla with ice water in preventing post-ERCP pancreatitis (ice water challenge study).

BACKGROUND: The most common adverse event of endoscopic retrograde cholangiopancreatography (ERCP) is post-ERCP pancreatitis (PEP). The aim of this study was to investigate the efficacy of cooling the papilla with iced water to reduce PEP. PATIENTS AND METHODS: Between December 2018 and July 2019, 100 consecutive patients with native papilla undergoing ERCP were prospectively enrolled in this study. In all patients, iced water was injected endoscopically toward the papilla via the working channel at the end of ERCP. The results were compared with 100 previous cases with native papilla that underwent ERCP under the same conditions without papilla cooling. RESULTS: Although the difference was not significant, the incidence of PEP tended to be lower in the study group (4%) than in the control group (11%) (p = 0.060). In addition, the incidence of PEP was significantly reduced in patients who underwent biliary sphincterotomy (p = 0.033). All cases of PEP were mild. CONCLUSIONS: Cooling the papilla with iced water injection, which is safe, easy, and cheap might reduce PEP.

Diagnostic Reference Levels for Fluoroscopy-guided Gastrointestinal Procedures in Japan from the REX-GI Study: A Nationwide Multicentre Prospective Observational Study.

BACKGROUND: Diagnostic reference levels (DRLs) are required to optimize medical exposure. However, data on DRLs for interventional fluoroscopic procedures are lacking, especially in gastroenterology. This study aimed to prospectively collect currently used radiation doses and help establish national DRLs for fluoroscopy-guided gastrointestinal procedures in Japan. METHODS: This multicentre, prospective, observational study collected actual radiation dose data from endoscopic retrograde cholangiopancreatography (ERCP), interventional endoscopic ultrasound (EUS), balloon-assisted enteroscopy (BAE), enteral metallic stent placement, and enteral tube placement from May 2019 to December 2020. The study outcomes were fluoroscopy time (FT: min), air kerma at the patient entrance reference point (Ka,r: mGy), air kerma area product (PKA: Gycm2), and radiation dose rate (RDR: mGy/min). Additionally, the basic settings of fluoroscopy equipment and the factors related to each procedure were investigated. This study was registered in the UMIN Clinical Trial Registry (UMIN 000036525). FINDINGS: Overall, 12959 fluoroscopy-guided gastrointestinal procedures were included from 23 hospitals in Japan. For 11162 ERCPs, the median/third quartile values of Ka,r (mGy), PKA (Gycm2), and FT (min) were 69/145 mGy, 16/32 Gycm2, and 11/20 min, respectively. Similarly, these values were 106/219 mGy, 23/41 Gycm2 and 17/27 min for 374 interventional EUSs; 53/104 mGy, 16/32 Gycm2 and 10/15 min for 523 metallic stents; 56/104 mGy, 28/47 Gycm2, and 12/18 min for 599 tube placements; and 35/81 mGy, 16/43 Gycm2 and 7/15 min for 301 BAEs, respectively. For the overall radiation dose rate, the median/third quartile values of RDR were 5.9/9.4 (mGy/min). The RDR values at each institution varied widely. INTERPRETATION: This study reports the current radiation doses of fluoroscopy-guided gastrointestinal procedures expressed as DRL quantities. This will serve as a valuable reference for national DRL values. FUNDING: This work was supported by a clinical research grant from the Japanese Society of Gastroenterology.

Multicenter prospective cohort study of adverse events associated with biliary endoscopic retrograde cholangiopancreatography: Incidence of adverse events and preventive measures for post-endoscopic retrograde cholangiopancreatography pancreatitis.

OBJECTIVES: The reported incidence of adverse events (AEs) in endoscopic retrograde cholangiopancreatography (ERCP) varies between 2.5% and 14%. The aim of this study was to evaluate the incidence and severity of AEs in biliary ERCP and to specify the risk factors and preventive measures for post-ERCP pancreatitis (PEP). METHODS: Patients with biliary disease with intact papilla were prospectively enrolled at 36 hospitals between April 2017 and March 2018. The primary outcomes were the incidence and severity of AEs. RESULTS: A total of 16,032 ERCP procedures were performed at the 36 hospitals during the study period and 3739 patients were enrolled. The overall incidence of AEs was 10.1% and ERCP-related mortality was 0.08%. PEP developed in 258 cases (6.9%), bleeding in 33 (0.9%), instrumental AEs in 17 (0.5%), infections in 37 (1.0%), cardiovascular AEs in eight (0.2%), pulmonary AEs in eight (0.2%), drug reaction AE in one (0.03%), pain in 15 (0.4%), and other AEs in 15 (0.4%). Multivariable analysis showed significant risk factors for PEP were: female of younger age, pancreatic guidewire-assisted biliary cannulation, temporary guidewire insertion into the pancreatic duct, total procedure time >60 min, and post-ERCP administration of non-steroidal anti-inflammatory drugs. Effective preventive measures were prophylactic pancreatic stenting (PPS) and epinephrine spraying onto the papilla. CONCLUSIONS: In patients with intact papilla who underwent biliary ERCP, the incidence of AEs was 10.1% and the mortality was 0.08%. PPS and epinephrine spraying may prevent PEP. REGISTRATION: This study was registered in the University Hospital Medical Information Network (UMIN000024820).

Stent placement above the sphincter of Oddi is a useful option for patients with inoperable malignant hilar biliary obstruction.

BACKGROUND AND AIMS: Endoscopic biliary drainage (EBD) is essential for the management of malignant hilar biliary obstruction (MHBO). We prospectively evaluated the efficacy and safety of "inside-stent" therapy, where a plastic stent is placed above the sphincter of Oddi without endoscopic sphincterotomy, in patients with inoperable MHBO. METHODS: This study was a multicenter, single-blinded, randomized controlled trial at three centers. Patients with inoperable MHBO were enrolled in this study, and randomly assigned to receive an inside-stent or conventional-stent therapy. The primary endpoint was cumulative stent patency of the initial stent. The secondary endpoints were second stent patency, technical and clinical success rate, adverse events, re-intervention rate, and overall patient survival. RESULTS: Forty-three patients were randomly assigned to the inside-stent group (n = 21) or the conventional-stent group (n = 22). The median cumulative stent patency of the initial stent was 123 days in the inside-stent group and 51 days in the conventional-stent group (P = .031). For patients with the initial stent dysfunction in the conventional-stent group, the inside-stent was placed as a second stent, and its patency was significantly longer than that of the initial stent (P = .0001). The technical and clinical success rate, re-intervention rate, second stent patency, adverse events, and survival probability did not differ between the groups. CONCLUSIONS: Inside-stent therapy appears to be useful not only as an initial stent but also as a second stent for patients with inoperable MHBO. TRIAL REGISTRATION NUMBER: UMIN000004587.

Long-term Outcomes of Stent Placement Inside the Bile Duct for Biliary Strictures After Living Donor Liver Transplantation.

In living donor liver transplantation (LDLT), anastomotic biliary stricture is a serious and refractory complication. In this study, we reviewed the transition of post-LDLT anastomotic biliary strictures and evaluated long-term outcomes of stent placement inside the bile duct, which is referred to as an "inside-stent." Of 805 consecutive adult LDLT recipients in our institution (2000-2018), we reviewed 639 patients with duct-to-duct biliary reconstruction and analyzed chronological changes of post-LDLT biliary strictures. Moreover, we focused on the year 2006 when various surgical modifications were introduced and compared the details of post-LDLT biliary strictures before and after 2006, especially focusing on the long-term outcome of inside-stent placement. The proportion of left lobe grafts had increased from 1.8% before 2005 to 39.3% after 2006 (P < 0.001) to maximize the living donor safety. Overall, post-LDLT anastomotic biliary strictures occurred in 21.3% of the patients with a median follow-up period of 106.1 months, which was decreased from 32.6% before 2005 to 12.8% after 2006 (P < 0.001). Anastomotic biliary strictures were less frequent in patients with left lobe grafts than with right lobe grafts (9.4% versus 25.4%; P < 0.001). The overall technical success rate of inside-stent placement was 82.4%, with an improvement from 75.3% before 2005 up to 95.7% after 2006 (P < 0.01). Furthermore, the stricture resolution rate remained high at approximately 90% throughout the observation period. Increased use of left lobe grafts with several surgical modifications significantly reduced post-LDLT anastomotic biliary strictures, leading to favorable long-term outcomes of inside-stent placements for this condition.

New practical scoring system to predict post-endoscopic retrograde cholangiopancreatography pancreatitis: Development and validation.

BACKGROUND AND AIM: Post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP) is the most serious adverse event of ERCP. Therefore, it is important to identify high-risk patients who require prophylactic measures. The aim of this study was to develop a practical prediction model for PEP that identifies high-risk patients. METHODS: Patients who underwent ERCP at three tertiary hospitals between April 2010 and September 2012 were enrolled. The dataset was divided into a training set (two centers) and validation set (one center). Using the training set, univariable and multivariable analyses were performed to identify predictive factors for PEP. We constructed a scoring system and evaluated reproducibility using the validation set. RESULTS: A total of 2719 ERCPs were analyzed. PEP developed in 133 cases (4.9%). Risk factors (adjusted odds ratios [OR]) in the training set were a history of PEP (OR: 4.2), intact papilla (OR: 2.4), difficult cannulation (OR: 1.9), pancreatic guidewire-assisted biliary cannulation (OR: 2.2), pancreatic injection (OR: 2.1), pancreatic intraductal ultrasonography (IDUS)/sampling from the pancreatic duct (OR: 2.2), and biliary IDUS/sampling from the biliary tract (OR: 2.8). A scoring system was constructed using these seven clinical variables. The areas under the receiver-operating characteristic curve of this model were 0.799 in the training set and 0.791 in the validation set. In the high-risk group at a score of 3 or higher, the incidence of PEP was 13.4%, and all severe/fatal cases were in the high-risk group. CONCLUSIONS: This scoring system helps to predict each patient's risk and select preventive measures.

High signal intensity on diffusion-weighted magnetic resonance images is a useful finding for detecting early-stage pancreatic cancer.

PURPOSE: Early detection of pancreatic ductal adenocarcinoma (PDAC) may improve the prognosis. We evaluated novel imaging findings that may contribute to early detection. METHODS: This single-center, retrospective study enrolled 37 patients with a localized main pancreatic duct (MPD) stricture and no obvious pancreatic mass. All patients underwent endoscopic retrograde cholangiopancreatography and brush sampling with cytology and serial pancreatic juice aspiration cytologic examination via endoscopic naso-pancreatic drainage. Patients with cytology-confirmed malignancy underwent surgical resection. The remaining patients were followed by contrast-enhanced computed tomography (CECT), magnetic resonance imaging (MRI), and endoscopic retrograde cholangiopancreatography. RESULTS: Twenty patients had confirmed malignancy (cancer group) and 17 did not (non-cancer group). Age, MPD stricture location, and PDAC risk factors were similar, but the sex predominance and symptom rate differed between the two groups. In the cancer group, 17 patients were diagnosed by cytology and three by clinical symptoms. CECT, MRI, and endoscopic ultrasonography (EUS) revealed no solid tumors in either group. CECT revealed no significant differences between groups. Diffusion-weighted MRI revealed significant differences in the signal intensity between groups. EUS detected indistinct and small hypoechoic areas in 70% and 41.2% of patients in the cancer and non-cancer groups, respectively. In the cancer group, 11 were diagnosed with cancer at the first indication, and nine were diagnosed at follow-up; the prognosis did not differ between these two subgroups.ss CONCLUSIONS: High signal intensity in diffusion-weighted MRI may be useful for detecting early-stage PDAC and may be an indication for surgical resection even without pathologic confirmation. CLINICAL TRIAL REGISTRATION: The study was a registered at the University Hospital Medical Information Network (UMIN000039623).

Risk factor analysis for early rebleeding after endoscopic treatment for colonic diverticular bleeding with stigmata of recent hemorrhage.

BACKGROUND AND AIM: Colonic diverticular bleeding is a common cause of acute lower gastrointestinal bleeding. Endoscopic hemostasis is generally selected as the first-line treatment; however, a considerable number of patients experience early rebleeding after endoscopic treatment. We investigated the risk factors for early rebleeding after endoscopic treatment. METHODS: We retrospectively evaluated the data of 142 consecutive patients who underwent endoscopic treatment (endoscopic clipping or endoscopic band ligation) for colonic diverticular bleeding with stigmata of recent hemorrhage between April 2012 and April 2020. Multivariate logistic regression analysis was conducted to evaluate the statistical relationship between patient characteristics and the incidence of early rebleeding occurring within 30 days after endoscopic treatment. RESULTS: Of 142 patients, early rebleeding was detected in 34 (23.9%) patients. According to univariate analysis, platelet count of <10 × 104/µL, bleeding from the left-sided colon, and endoscopic clipping usage were associated with early rebleeding (P < 0.05). The subsequent multivariate logistic regression analysis identified bleeding from the left-sided colon (odds ratio [OR], 4.16; 95% confidence interval [CI], 1.73-10.0; P = 0.001) and endoscopic clipping usage (OR, 2.92; 95% CI, 1.21-7.00; P = 0.017) as the independent risk factors for early rebleeding. CONCLUSIONS: Bleeding from the left-sided colon and endoscopic clipping usage were the risk factors for early rebleeding after endoscopic treatment. Using endoscopic band ligation was associated with a decreased risk for early rebleeding compared with the use of endoscopic clipping, indicating that endoscopic band ligation was a preferable endoscopic modality to prevent early recurrent bleeding.

An unusual tumor of the bile duct.

Highlight Sawada and colleagues report a case of mucinous cholangiocarcinoma not originating from intraductal papillary neoplasm of the bile duct. While recognizing the imaging features of the bile ducts is difficult due to their narrow area, the detailed characteristic features may enable preoperative diagnosis of this rare type of cholangiocarcinoma.

Utility of a 20G needle with a core trap in EUS-guided fine-needle biopsy for gastric submucosal tumors: A multicentric prospective trial.

BACKGROUND AND OBJECTIVES: Differential diagnosis to estimate the malignant potential of gastric submucosal tumor (g-SMT) is important for decision-making. This study evaluated the use of a 20G needle with a core trap for EUS-guided fine-needle biopsy (EUS-FNB) for g-SMT. METHODS: This multicentric prospective trial was registered in the University Hospital Medical Information Network (UMIN000021410). Consecutive patients with g-SMT who presented at one of the nine Japanese Referral Centers between June 2017 and November 2018 were enrolled. All patients underwent EUS-FNB using a 20G needle with a core trap. Samples obtained with the first-needle pass were used for central pathological review. EUS-FNB was evaluated in terms of (i) technical success rate, (ii) adequacy for histological evaluation, (iii) rate of complications, (iv) accuracy for histological diagnosis of gastrointestinal stromal tumor (GIST), and (v) concordance between GIST mitotic index determined by EUS-FNB and after tumor resection. RESULTS: The study included 52 patients. The technical success rate of EUS-FNB was 100%. The adequacy rate for histological evaluation was 90.4% (P < 0.001). There were no complications related to EUS-FNB. Of the 38/52 patients who underwent surgical resection, 36 were finally diagnosed with GIST. The sensitivity, specificity, and accuracy of EUS-FNB for the histological diagnosis of g-SMT were 80.6%, 100%, and 81.6%, respectively. The concordance rate between the mitotic index on EUS-FNB and that after analysis of the resected tumor was 89.7%. CONCLUSIONS: EUS-FNB using a 20G needle with a core trap is feasible, providing histological samples of sufficient quality for diagnosing g-SMT.