Effect of aging on the adult extrahepatic bile duct: A sonographic study

Objective. To determine whether the size of the extrahepatic bile duct increases with age in adults. Methods. We prospectively collected data on 251 patients aged 20 years or older who underwent abdominal sonography. None of the patients had a history of liver, gallbladder, biliary, or pancreatic disease or surgery. The extrahepatic bile duct was measured at 3 locations: in the porta hepatis, in the most distal aspect of the head of the pancreas, and midway between these points. Least squares linear regression was used to correlate patient age and the size of the extrahepatic bile duct. Results. There were 126 men and 125 women aged 20 to 94 years (mean ± SD, 52.5 ± 17.63 years). Twelve percent of the study population were younger than 30 years, and 12% were older than 80 years. The mean diameters of the common bile duct in the 3 locations were as follows: proximal, 3.39 ± 1.14 mm; middle, 3.72 ± 1.28 mm; and distal, 4.28 ± 1.18 mm. The overall mean for all measures was 3.66 ± 1.15 mm. The width of the common bile duct ranged from 1.0 to 8.6 mm. There was a significant correlation between common bile duct size and age (r = 0.535; P < .001). Mean common bile duct sizes were 3.128 ± 0.862 mm in the patients younger than 50 years and 4.19 ± 1.15 mm in the patients older than 50 years (P < .001 by independent t test for equality of means). We have found that the duct gradually dilated 0.04 mm/y. Conclusions. This study revealed an age-dependent change in the diameter of the extrahepatic bile duct. We suggest that the upper normal limit of the duct in elderly persons be set at 8.5 mm.