Temporal Changes in Biliary Duct Diameter with Correlated Bilirubin Levels in Confirmed Choledocholithiasis: A Prospective 3 Time‐Point Observational Ultrasound Study

OBJECTIVES: Choledocholithiasis often coexists with symptomatic cholelithiasis, and early detection is crucial to prevent complications. In these patients, the common bile duct (CBD) may appear non-dilated on ultrasonography (US). Studies on the temporal evolution of CBD measurements and corresponding bilirubin levels are currently lacking. Herein, we aim to evaluate the temporal evolution and correlation of CBD/intrahepatic duct (IHD) dilatation with serum bilirubin levels in patients with choledocholithiasis. METHODS: In this single-center prospective study, we included 46 patients with acute right upper quadrant pain, sonographically confirmed cholelithiasis and MRCP/ERCP confirmed choledocholithiasis. CBD/IHD US measurements and serum total/direct bilirubin levels were obtained at <24 (t1), 24-48 (t2), and 48-72 hours (t3). Serial CBD/IHD diameters were correlated with bilirubin concentrations. Statistical significance was set at p < .01. RESULTS: Prevalence of CBD dilatation increased from 34.8% at t1 to 69.6% at t2 and 95.7% at t3. Mean CBD diameters increased from 5.7 ± 2.3 mm to 8.2 ± 2.7 mm and 12.1 ± 2.5 mm (p < .0001). IHD dilatation incidence increased from 2.1 to 19.6% and 78.3%. Total/direct bilirubin levels progressed between all time-points, with the greatest increase between t1 and t3 (p = .0003/p = .0006). Sensitivity of CBD dilatation for diagnosing choledocholithiasis was 34.8, 69.6, and 95.7% increasing to 56.5%/78.3%, 87%/91.3% and 95.7%/95.7% when combined with total/direct bilirubin across t1, t2, and t3, respectively. CONCLUSIONS: In patients with choledocholithiasis, emergency US may be false-negative. Serial US assessment of CBD diameter, particularly when combined with bilirubin trends, substantially improves diagnostic sensitivity. Repeat US and laboratory investigations within up to 3 days are supported for appropriate patient management.