Trondsen et al developed a discriminant function to identify a patient who probably has common bile duct stones and who may benefit from ERCP prior to cholecystectomy. This can reduce the number of ERCP procedures that are unnecessary. The authors are from Central Hospital of Akershus in Norway.



(1) age in years

(2) serum total bilirubin in µmol/L

(3) serum ALT in IU/L

(4) serum GGT in IU/L


discriminant function =

= (0.06617 * (age in years)) + (0.0260967 * (bilirubin)) + (0.00832 * (ALT)) + (0.0088144 * (GGT)) - 7.58525


Indications for ERCP - either of the following:

(1) a positive value for the discriminant function

(2) presence of gallstone pancreatitis



• The sensitivity for detecting CBD stones was 94% and specificity was 88%.



• The reference ranges for ALT and GGT were not given.


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