Scoring system to preoperatively predict choledocholithiasis.

Background: The incidence of common bile duct (CBD) calculi has been reported to be 8 % to 20 % among the patients with cholelithiasis. Failure to detect CBD stones on the part of the surgeon not only fails to relieve symptoms but also subjects them to potentially life-threatening complications such as cholangitis, pancreatitis or obstructive jaundice. Modalities for detection of CBD stones have evolved over time from CBD exploration based on clinical and operative findings to intraoperative cholangiography (IOC), to endoscopic retrograde cholangiopancreaticography (ERCP) and, recently, to magnetic resonance cholangiopancreaticography (MRCP) and endoscopic ultrasonography (EUS). We felt a need for a scoring system to predict a patient population having a higher risk of choledocholithiasis so that these modern interventions can be selectively utilized.

Setting: This study was performed in a tertiary care medical college hospital in a metropolitan city.

Design: This is a prospective observational study.

Methods: All patients with symptomatic cholelithiasis admitted to the hospital were included. Patients were diagnosed as having choledocholithiasis either by ultrasonography (USG), computed tomography scan, MRCP, EUS or ERCP and were followed up for at least 6 weeks.

Results: The prevalence of choledocholithiasis among the 275 patients with symptomatic biliary colic in our study was 18.9 % (n = 77). On bivariate analysis, dilated bile duct on USG (>6 mm), raised total bilirubin, raised alkaline phosphatase (ALP), raised amylase, raised SGPT and SGOT were significantly associated with choledocholithiasis (p < 0.05). On multivariate analysis also, all these factors except amylase and SGPT showed a significant correlation with choledocholithiasis (p < 0.05). These observations were used to build a scoring system consisting of four factors: dilated bile duct on USG (>6 mm), total bilirubin >2 mg/dL, ALP >190 IU/L and SGOT >40 IU/L.

Conclusion: A positive predictive value of 3 or more factors was over 95 %, necessitating an endoscopic intervention. A negative predictive value of the absence of any factor was 100 %, which ruled out CBD calculi. If only one or two factors are positive, then further evaluation is recommended preferably using non-minimal or minimal invasive investigations like EUS or MRCP.