Value of ultrasound and liver function tests in determining the need for endoscopic retrograde cholangiopancreatography in unexplained abdominal pain.

The value of serum liver function tests and abdominal ultrasound as screening tests of the need for endoscopic retrograde cholangiopancreatography (ERCP) was determined in patients with unexplained abdominal pain without associated jaundice. In 1989 and 1990 1005 ERCPs were undertaken, of which 138 (14%) were for this indication. The duct or ducts of interest were delineated by ERCP in 95% of patients. The lesions found were bile duct stones in 10 patients, chronic pancreatitis in five, pancreatic carcinoma in one, peptic ulcer or duodenitis in four. A satisfactory ultrasound examination had been performed in 94% of patients. For chronic pancreatitis, its sensitivity was 60% and specificity 95%. For choledocholithiasis, the ultrasonic detection of duct dilatation or stones had a sensitivity of 90% and specificity of 86%. Of the liver function tests, the alkaline phosphatase was more sensitive (67%) than the transaminases (44%) in indicating the presence of bile duct stones and had a high specificity (95%). None of the 10 patients with duct stones had normal ultrasound and normal alkaline phosphatase. Thus it was found that demonstration of a normal common bile duct by abdominal ultrasound and normal serum alkaline phosphatase together have 100% specificity in excluding bile duct stones. Using such knowledge over the two year period of this study would have spared 36 patients the need for ERCP.