Retrospective Study
Copyright ©The Author(s) 2022. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastrointest Endosc. Jun 16, 2022; 14(6): 376-386
Published online Jun 16, 2022. doi: 10.4253/wjge.v14.i6.376
Endoscopic ultrasound diagnostic gain over computed tomography and magnetic resonance cholangiopancreatography in defining etiology of idiopathic acute pancreatitis
Stefano Mazza, Biagio Elvo, Clara Benedetta Conti, Andrea Drago, Maria Chiara Verga, Sara Soro, Annalisa De Silvestri, Fabrizio Cereatti, Roberto Grassia
Stefano Mazza, Andrea Drago, Maria Chiara Verga, Sara Soro, Roberto Grassia, Gastroenterology and Digestive Endoscopy Unit, ASST Cremona, Cremona 26100, Italy
Biagio Elvo, Gastroenterology and Endoscopy Unit, Federico II University, Napoli 80131, Italy
Clara Benedetta Conti, Interventional Endoscopy Unit, ASST Monza, Monza 20900, Italy
Annalisa De Silvestri, Biometry and Clinical Epidemiology, Scientific Direction, IRCCS San Matteo Hospital Foundation, Pavia 27100, Italy
Fabrizio Cereatti, Department of Gastroenterology and Digestive Endoscopy, Castelli Hospital, Ariccia (Rm) 00040, Italy
Author contributions: All authors contributed to literature search and data collect; Mazza S, Elvo B and Grassia R wrote the paper; Mazza S and De Silvestri A performed the statistical analysis; Conti CB, Drago A, Verga MC, Soro S and Cereatti F critically revised the paper and contributed to the final version of the manuscript.
Institutional review board statement: Approval by Ethics Committee of our Center was not required because of the retrospective nature of the study.
Informed consent statement: Patients were not required to give informed consent to the study because the analysis used anonymous clinical data that were obtained after each patient agreed to treatment by written consent.
Conflict-of-interest statement: All authors have no financial relationships to disclose.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Corresponding author: Stefano Mazza, MD, Doctor, Gastroenterology and Digestive Endoscopy Unit, ASST Cremona, Viale Concordia, 1, Cremona 26100, Italy.
Received: January 28, 2022
Peer-review started: January 28, 2022
First decision: April 10, 2022
Revised: April 23, 2022
Accepted: May 22, 2022
Article in press: May 22, 2022
Published online: June 16, 2022

About 10%-30% of acute pancreatitis remain idiopathic (IAP) even after clinical and imaging tests, including abdominal ultrasound (US), contrast-enhanced computed tomography (CECT) and magnetic resonance cholangiopancreatography (MRCP). This is a relevant issue, as up to 20% of patients with IAP have recurrent episodes and 26% of them develop chronic pancreatitis. Few data are available on the role of EUS in clarifying the etiology of IAP after failure of one or more cross-sectional techniques.


To evaluate the diagnostic gain after failure of one or more previous cross-sectional exams.


We retrospectively collected data about consecutive patients with AP and at least one negative test between US, CECT and MRCP, who underwent linear EUS between January 2017 and December 2020. We investigated the EUS diagnostic yield and the EUS diagnostic gain over different combinations of these cross-sectional imaging techniques for the etiologic diagnosis of AP. Types and frequency of EUS diagnosis were also analyzed, and EUS diagnosis was compared with the clinical parameters. After EUS, patients were followed-up for a median of 31.5 mo to detect cases of pancreatitis recurrence.


We enrolled 81 patients (63% males, mean age 61 ± 18, 23% with previous cholecystectomy, 17% with recurrent pancreatitis). Overall EUS diagnostic yield for AP etiological diagnosis was 79% (20% lithiasis, 31% acute on chronic pancreatitis, 14% pancreatic solid or cystic lesions, 5% pancreas divisum, 5% autoimmune pancreatitis, 5% ductal abnormalities), while 21% remained idiopathic. US, CECT and MRCP, taken alone or in combination, led to AP etiological diagnosis in 16 (20%) patients; among the remaining 65 patients, 49 (75%) obtained a diagnosis at EUS, with an overall EUS diagnostic gain of 61%. Sixty-eight patients had negative US; among them, EUS allowed etiological diagnosis in 59 (87%). Sixty-three patients had a negative CECT; among them, 47 (74%) obtained diagnosis with EUS. Twenty-four had a negative MRCP; among them, 20 (83%) had EUS diagnosis. Twenty-one had negative CT + MRCP, of which 17 (81%) had EUS diagnosis, with a EUS diagnostic gain of 63%. Patients with biliary etiology and without previous cholecystectomy had higher median values of alanine aminotransferase (154 vs 25, P = 0.010), aspartate aminotransferase (95 vs 29, P = 0.018), direct bilirubin (1.2 vs 0.6, P = 0.015), gamma-glutamyl transpeptidase (180 vs 48, P = 0.006) and alkaline phosphatase (150 vs 72, P = 0.015) Chronic pancreatitis diagnosis was more frequent in patients with recurrent pancreatitis at baseline (82% vs 21%, P < 0.001). During the follow-up, AP recurred in 3 patients, one of which remained idiopathic.


EUS is a good test to define AP etiology. It showed a 63% diagnostic gain over CECT + MRCP. In suitable patients, EUS should always be performed in cases of IAP. Further prospective studies are needed.

Keywords: Endoscopic ultrasound, Idiopathic acute pancreatitis, Diagnostic gain, Computed tomography, Magnetic resonance cholangiopancreatography

Core Tip: Acute pancreatitis (AP) is a common and potentially severe disease. Imaging techniques allow an etiological diagnosis in most cases. However, about 20% of cases remain idiopathic, with negative consequences on patients’ outcomes. Endoscopic ultrasound (EUS) has emerged as a valid technique for the assessment of AP etiology. We share our experience with EUS in the identification of idiopathic AP etiology, after failure of one or more cross-sectional imaging techniques. We found a superiority of EUS over the standard cross-sectional imaging techniques. We therefore suggest the use of EUS to define idiopathic AP etiology in all suitable patients.