Short segment involvement of the common bile duct in pancreatic carcinoma.

Short segment involvement of the midportion of the common bile duct by pancreatic carcinoma is common. It is generally not appreciated on transhepatic cholangiograms or during percutaneous drainage procedures since the uninvolved distal duct is rarely opacified. This pattern helps explain the ease of passing guidewires beyond the initial point of obstruction during drainage procedures. Knowledge of this anatomy may also have diagnostic and therapeutic significance. In some situations a special effort to opacify the distal duct may be warranted.