Gallstones are responsible for about half of the cases of acute pancreatitis in Europe and North America. 1-3 Although the exact mechanism of biliary pancreatitis is not understood, gallstone migration into the common bile duct is presumed to initiate pancreatitis. 2,4-6 Hypothesizing that the severity of acute biliary pancreatitis may be somehow related to the persistent presence of gallstones in the com- mon bile duct, studies have focused on evaluating the benefits of early endoscopic extraction of these stones. The first published randomized trial of urgent ERCP from England demonstrated that endoscopic sphincterotomy with stone extraction performed within 72 hours of admission decreased morbidity and shortened hospital stay in the sub- group of patients predicted to have severe pancre- atitis. 7 Subsequently, another randomized trial from Hong Kong that included patients with pancreatitis from causes other than gallstones demonstrated that emergent ERCP (with endoscopic sphincter- otomy when bile duct stones were identified) per- formed within 24 hours decreased the rate of biliary sepsis in all patients with pancreatitis. 8 However, a more recent randomized multicenter investigation Prospective assessment of the utility of EUS in the evaluation of gallstone pancreatitis Amitabh Chak, MD, Robert H. Hawes, MD, Gregory S. Cooper, MD, Brenda Hoffman, MD, Marc F. Catalano, MD, Richard C. K.Wong, MD,Thomas E. Herbener, MD, Michael V. Sivak, Jr., MD Cleveland, Ohio, Charleston, South Carolina, and Milwaukee, Wisconsin Background: The ability to identify common bile duct stones by noninvasive means in patients with acute biliary pancreatitis is limited. The aim of this study was to prospectively evaluate the ability of endosonography (EUS) to identify cholelithiasis and choledocholithiasis and predict disease severity in patients with nonalcoholic pancreatitis. Methods: EUS was performed immediately before endoscopic retrograde cholan- giopancreatography (ERCP) by separate blinded examiners within 72 hours of admis- sion. Gallbladder findings were compared between EUS and transabdominal ultra- sonography (US). Using endoscopic extraction of a bile duct stone as the reference standard for choledocholithiasis, the diagnostic yield of EUS was compared with transabdominal US and ERCP. Features identified during endosonographic imaging of the pancreas were correlated with length of hospitalization. Results: Thirty-six patients were studied. EUS and transabdominal US were con- cordant in their interpretation of gallbladder findings in 92% of patients. The sensi- tivity of transabdominal US, EUS, and ERCP for identifying choledocholithiasis was 50%, 91%, and 92% and the accuracy was 83%, 97%, and 89%, respectively. Length of hospital stay was longer in patients with peripancreatic fluid (9.2 vs. 5.7 days, p < 0.1) and shorter in patients with coarse echo texture (2.6 vs. 7.2 days, p < 0.05) demonstrated on EUS. Conclusions: EUS can reliably identify cholelithiasis and is more sensitive than transabdominal US in detecting choledocholithiasis in patients with biliary pan- creatitis. EUS may be used early in the management of patients with acute pan- creatitis to select those who would benefit from endoscopic stone extraction. The utility of EUS for predicting pancreatitis severity requires further investigation. (Gastrointest Endosc 1999;49:599-604.) Received March 3, 1998. For revision June 15, 1998. Accepted October 8, 1998. From the Division of Gastroenterology, Department of Radiology, University Hospitals of Cleveland, Cleveland, Ohio; Medical University of South Carolina, Charleston, South Carolina; and St. Luke’s Medical Center, Milwaukee, Wisconsin. Presented as a preliminary abstract at the annual meeting of the American Society for Gastrointestinal Endoscopy, Washington, D.C., May 11-14, 1997; and as a final abstract at the annual meet- ing of the ASGE, New Orleans, Louisianna, May 17-20, 1998. Supported in part (A.C.) by the Wilson Cook Endoscopic Research Scholar Award, 1997-98. Reprint requests: Amitabh Chak, MD, University Hospitals of Cleveland, 11100 Euclid Ave, Cleveland, OH 44106-1736. Copyright © 1999 by the American Society for Gastrointestinal Endoscopy 0016-5107/99/$8.00 + 0 37/1/95034 VOLUME 49, NO. 5, 1999 GASTROINTESTINAL ENDOSCOPY 599