Diameter of common bile duct: what are the predicting factors?

BACKGROUND: This was a study to determine the correlation between the common bile duct (CBD) diameter and demographic data, fasting, and the history ofopium addiction. METHODS: This was a cross-sectional study on 375 patients ( 16 years old) including 219 females and 156 males. They had no evident hepatobiliary or pancreatic disease and underwent abdominopelvic ultrasonography for measurement of their CBD diameter. Ultrasound (US) was performed to measure CBD diameter at the porta hepatis (proximal part) and behind the head of the pancreas (distal part). Correlation coefficients for the association between CBD diameter and predictive factors were calculated. t-test was applied to compare the means between the groups. RESULTS: The mean CBD diameter (l standard deviation), in proximal and distal parts were 3.64 mm ((PLUS- MINUS)1.2) and 3.72 mm ((PLUS- MINUS)1.2), respectively. The CBD diameters (proximal and distal) were significantly (P(LESS THAN)0.05) correlated with age (r = 0.55 and 0.54, respectively), BMI (r = 0.25 and 0.27, respectively) and portal vein diameter (r = 0.24 and 0.22, respectively). Distal diameter of CBD was significantly larger in opium addicts (5.66 (PLUS- MINUS) 2.65) in comparison with non addicts (3.68 (PLUS- MINUS) 1.17, P = 0.04). CONCLUSIONS: CBD diameter associates with age, BMI, portal vein diameter and opium addiction. CBD dilatation, if it can not be explained by age, opium usage or large BMI, should be evaluated further to rule out obstruction.