GS37P SELECTIVE MAGNETIC RESONANCE CHOLANGIO‐PANCREATOGRAPHY (MRCP) IN GALLSTONE PANCREATITIS MAY MISS CHOLEDOCHOLITHIASIS

Abstract

Purpose: Patients with Gallstone Pancreatitis (GP) have a high risk of choledocholithiasis. MRCP has been recommended by some as the investigation of choice to diagnose choledocholithiasis. This study examines the diagnostic value of selective MRCP in GP.Methodology: Retrospective audit of all presentations of GP between Jan 2001–December 2007 at Middlemore Hospital. Demographic data, clinical presentation, biochemical, radiological findings and outcomes were reviewed. Data were analysed using univariate analysis and chi‐squared test.Results: There were 339 cases of gallstone pancreatitis with 243 females and a mean age of 52 years. Overall, 95 cases of choledocholithiasis‐ as confirmed by ERCP/ Intra‐Operative Cholangiogram (IOC) – were diagnosed. The indications for MRCP in this study were heterogeneous. 117 patients underwent MRCP within a median of 4 days of admission with 15 (13.7%) showing choledocholithiasis. There was no significant difference in time to MRCP between positive and negative groups. ERCP/IOC confirmed 13/15 stones within a median of 2.5 days. MRCPs, however, missed 8 cases of choledocholithiasis subsequently demonstrated on ERCP/IOC where clinical suspicion remained after a negative MRCP. MRCP sensitivity was 62.0, specificity 97.9. The Positive Likelihood Ratio was 6.5, Negative Likelihood Ratio was 0.1. PPV was 86.7, NPV was 92.0. 222 patients followed different clinical pathways with 82 Common Bile Duct (CBD) stones diagnosed by ERCP/IOC.Conclusion: Choledocholithiasis is common in GP. Selective MRCP is highly specific in GP but may not be sensitive enough to exclude choledocholithiasis in this context.