Evaluation of unexplained acute pancreatitis using ERCP, sphincter of Oddi manometry(SOM), and endoscopic ultrasound (EUS)

The etiology of acute pancreatitis remains unexplained in up to one-third of patients after common causes are excluded. The aim of this study was to determine the diagnostic utility of ERCP with SOM combined with EUS in the evaluation of these patients. Methods: From July 1994 to Nov 1995,188 patients (age > 17 years) were referred for evaluation and/or treatment of pancreatitis. 93 pts had a known cause (alcohol, biliary, congenital, medications, metabolic, or trauma) and were excluded. The remainder (N= 68) were classified as prior acute (N=16) or recurrent acute (N=52) pancreatitis. All had a history of typical abdominal pain with elevation of pancreatic enzymes > 2 times normal. SOM was performed prior to contrast injection using a standard triple-lumen aspirating catheter. SOM was considered abnormal if basal pressures for both perfused leads were ≥ 40mmHg. Pancreatic ductography was graded according to the Cambridge classification of chronic pancreatitis. EUS was used to rule out tumors and to evaluate for chronic pancreatitis (≥ 3/7 features required). Results: ERCP was successful in 66/68 pts (97%). Manometry was attempted in 47 patients and successful in 44(94%). Forty-one patients underwent EUS (60%), Findings are summarized in the table below: Total SOD Divisum Biliary Anatomic*Idiopathic 68 24(35%) 11(16%) 10(15%) 7(10%) 16(24%)*Five patients with neoplasia and 2 with choledochocele Seven of 24 patients (29%) with SOD had isolated pancreatic sphincter hypertension (PSH); 5 of these had prior biliary sphincterotomy (Bsx). Eighteen patients (26%) had features of moderate or severe chronic pancreatitis by EUS and ERCP criteria; an additional 6 patients (9%) had chronic pancreatitis by EUS criteria alone. EUS identified all tumors and obviated the need for ERCP in one patient with pancreatic cancer. A biliary cause was identified in two patients by EUS only. Summary: A specific etiology was identified in the majority of pts (76%) with unexplained pancreatitis using advanced endoscopic techniques. SOD represents the most common finding and PSH is an important cause of acute pancreatitis in patients after Bsx. Moderate to severe chronic pancreatitis by endoscopic criteria (particularly EUS) was found in one-third of these patients. Conclusion: ERCP with SOM is an essential tool when evaluating unexplained acute pancreatitis. EUS is also valuable in this population especially for detection of biliary and anatomic abnormalities as well as unsuspected chronic pancreatitis.