PWE-201 Magnetic resonance cholangiopancreatography should be the gold standard versus routine ultrasonography for gallstone pancreatitis

Introduction Acute gallstone pancreatitis may be caused by distal obstruction of the common bile duct, abnormal liver function tests (LFTs) and biliary ultrasonography (US) have been used to select those patients who should undergo magnetic resonance cholangiopancreatography (MRCP) and or subsequent endoscopic retrograde cholangiopancreatography (ERCP). The aim of this study was to compare the accuracy of predicting choledocholithiasis using abnormal LFTs and biliary US compared to routine MRCP. Method All patients admitted between January 2012 to March 2014 identified with gallstone pancreatitis (amylase >300μL) were included in the study. Retrospective admission LFTs, US and MRCP reports were collated. Results Overall, 122 patients were admitted with gallstone pancreatitis and 47 patients underwent subsequent MRCP. Choledocholithiasis was seen in 55% (26/47). The mean bilirubin was higher in those with choledocholithiasis (18μmol/l (3–74) versus 44μmol/l (8–232) and ALP (134iμ/l (32–690) versus 196iμ/l (48–697). Abnormal bilirubin (>21μmol) was associated with choledocholithiasis demonstrated at MRCP with a sensitivity of 65.38% (95% CI 44.33–87.79%) and specificity 57.14% (95% CI 43.22–70.29%) with a positive predictive value (PPV)of 68.4% (p = 0.007); ALP (>140iμ/l) sensitivity 73.08% (95% CI 80.36–99.9%) and specificity 57.14% (95% CI 43.22–70.29%) with a PPV of 63% (p = 0.04) and ALT (>53iμ/l) sensitivity 96.15 (95% CI 80.46–99.9%) and specificity 41.07% (95% CI 28.10–55.02%) with a PPV of 72.7% (p = 0.0009). Combined abnormal bilirubin, ALP and ALT for choledocholithiasis had a positive predictive value of 63% (p = 0.04). US demonstrated biliary duct dilation was not significantly associated with abnormal bilirubin, ALP or ALT. Furthermore, biliary duct dilatation on US had a sensitivity of 19.23% (95% CI 6.55–39.35%) and specificity 86.21% (95% CI 74.62–93.85) with a PPV 52% (P = 0.69) and was not significantly associated with choledocholithiasis demonstrated at MRCP. Conclusion MRCP should be the gold standard to investigate all patients with gallstone pancreatitis with abnormal LFTs as US biliary dilation alone or associated with abnormal LFTs is a poor predictor of common bile duct stones. Disclosure of interest None Declared.