Extrahepatic bile ducts in healthy subjects, in patients with cholelithiasis, and in postcholecystectomy patients: a prospective ultrasonic study.

To determine the average diameter and the upper normal limit of the common bile duct in healthy man, 830 blood donors were examined by ultrasound. The mean diameter was 2.5 +/- 1.1 mm (SD) at the porta hepatis and 2.8 +/- 1.2 mm (SD) at the widest point, the regression coefficient between both diameters being r = 0.84. None of the healthy subjects had a diameter larger than 7 mm at any site, and in 95% of all subjects the diameters were less than 4 mm at both sites of measurement. The diameters were significantly correlated with age (r = 0.16) and weight (r = 0.11), but not with sex, height, and body surface area. In 73 patients with cholelithiasis and in 55 patients after cholecystectomy, all of whom lacked clinical or laboratory signs of biliary obstruction, the average diameters at the porta hepatis were 3.8 +/- 2.0 mm and 5.2 +/- 2.3 mm, and at the widest point 4.8 +/- 2.2 mm and 6.2 +/- 2.5 mm, respectively. It is concluded that a common bile duct with any sonographic diameter larger than 4 mm should be followed closely and evaluated further with clinical examinations such as intravenous cholangiography unless cholecystectomy has been performed.