Detection of gall stones after acute pancreatitis

Four methods of gall stone diagnosis after an attack of acute pancreatitis are analysed. Of 128 consecutive patients with acute pancreatitis, 99 patients were discharged from hospital without a definite aetiology. These patients had biochemical tests performed on admission and ultrasonography and oral cholecystography performed six weeks later. The sensitivity for ultrasonography was 87% and the specificity was 93%; the respective figures for oral cholecystography were 83% and 90%. The predictive value of positive ultrasonography was 100% and of negative ultrasonography 75%; the respective values for oral cholecystography were 95% and 68%. A combination of ultrasonography and oral cholecystography failed to detect nine of 70 patients with gall stones (13%). Of 35 patients with normal ultrasonography and oral cholecystography, 33 patients had an endoscopic retrograde cholangiogram (ERCP) which showed gall stones in a further seven patients. All three methods failed to reveal gall stones in two patients, confirmed by laparotomy. The sensitivity of admission biochemical analysis was 73% and the specificity was 94%; the predictive value of a positive result was 97% and of a negative result was 57%. Biochemical analysis predicted gall stones in six of the seven patients shown by ERCP. Only 9% of patients were finally considered to be idiopathic. In conclusion ultrasonography is the investigation of choice and ERCP should be undertaken in all patients who have normal ultrasonography and/or oral cholecystography but have biochemical criteria indicative of gall stones.