Diagnostic yield of ERCP and secretin-enhanced MRCP and EUS in patients with acute recurrent pancreatitis of unknown aetiology.

BACKGROUND: Magnetic resonance cholangio-pancreatography (MRCP), endoscopic ultrasonography (EUS), and endoscopic cholangio-pancreatography (ERCP) are the most frequently employed second-step procedures to detect biliary and pancreatic abnormalities in patients with acute recurrent pancreatitis (ARP) of unknown aetiology. MRCP and EUS both give a better view of the bilio-pancreatic ductal system after secretin stimulation (MRCP-S, EUS-S). EUS also serves to identify changes in the pancreatic parenchyma consistent with chronic pancreatitis, at an early stage. However, no studies have compared MRCP-S, EUS-S, and ERCP in the diagnosis of recurrent pancreatitis.

AIM: To prospectively compare the diagnostic yield of MRCP-S, EUS-S, and ERCP in the evaluation of patients with acute recurrent pancreatitis with non-dilated ducts, of unknown aetiology.

METHODS: Forty-four consecutive patients with ARP were prospectively scheduled to undergo MRCP-S, EUS-S and ERCP, in accordance with a standard protocol approved by the institutional review board. Diagnoses such as biliary microlithiasis, congenital variants of the pancreatic ducts, chronic pancreatitis and sphincter of Oddi dysfunction were compared between the three procedures. The diagnosis of chronic pancreatitis was established according to ductal morphology by MRCP-S and ERCP, ductal and parenchymal morphology by EUS-S.

RESULTS: The three procedures combined achieved a diagnosis that could have explained the recurrence of pancreatitis in 28/44 patients (63.6%). EUS-S recognized ductal and/or parenchymal abnormalities with the highest frequency (35/44 patients, 79.5%). Both MRCP-S and EUS-S were superior to ERCP for detecting pancreatic ductal abnormalities. EUS-S showed up pancreatic parenchymal changes in more than half the cases. Both EUS and MRCP secretin kinetics were concordant in identifying two cases with sphincter of Oddi dysfunction.

CONCLUSIONS: The diagnostic yield of EUS-S in recurrent pancreatitis with non-dilated ducts and unknown aetiology was 13.6% and 16.7% higher than MRCP-S and ERCP respectively (although not significant), which both gave substantially similar diagnostic yields. In no case did ERCP alone find a diagnosis missed by the other two procedures. MRCP-S and EUS-S should both be used in the diagnostic work-up of idiopathic recurrent pancreatitis as complementary, first-line, techniques, instead of ERCP.