(Ultrasound Review) In order to determine whether the extrahepatic bile duct diameter increases with age, radiologists at Rabin Medical Center in Tel Aviv, used ultrasound to scan the bile duct in 251 consecutive patients over the age of 19 years. The results of this prospective study were published in the Journal of Ultrasound in Medicine.
Patients with a history of liver, biliary or pancreatic surgery, disease or abnormality were not included. Gallbladder distension was achieved by observing a six to 12 hour fast. A 2-4 MHz convex array transducer was used for abdominal imaging, and color Doppler was used to define vessels and anatomy at the porta hepatis.
The investigators observed a wide variation in AP diameter from the porta hepatis to the distal aspect at the head of the pancreas. Measurements were performed using electronic calipers at three locations -- porta hepatis, head of pancreas and midway between these two points.
"Our study shows that the width of the CBD differs greatly among the 3 locations, with mean ± SD values of 3.39 ± 1.14 mm proximally, 3.72 ± 1.28 mm at the middle, and 4.28 ± 1.18 mm distally," they determined. In the 10 patients aged 48 to 85 years, the diameter at the point half way between the porta hepatis and the pancreatic head was the widest.
"The enlargement of the bile ducts in elderly subjects may be explained by the characteristic fragmentation of the longitudinal smooth myocyte bands and interspersed connective tissue combined with the decrease in the reticular-elastic framework of the duct wall over time, which leads to reduced contractility and hypotonus of the CBD," they reported.
The authors recommended that 8.5 mm be considered the upper limit of normal in elderly patients when measuring the AP diameter of the CBD in the long axis.
"In conclusion, this study showed an age-dependent change in the diameter of the extrahepatic bile duct. We suggest that the upper normal limit of the duct in the elderly should be set at 8.5 mm," they said.
Effect of aging on the adult extrahepatic bile duct -- A sonographic studyBachar, G. N., et. al.
Department of radiology, Rabin Medical Center, Tel Aviv University.
J Ultrasound Med 2003 September; 22:879-882
By Ultrasound Review
October 22, 2003
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