The pseudo-dilated common bile duct: ultrasonographic appearance created by the gallbladder neck.

A retrospective analysis of 111 ultrasonograms was performed in order to evaluate the relationship of the gallbladder neck to the common bile duct and portal vein. Of the 100 studies deemed technically adequate, eight contained scans that demonstrated a potentially confusing pattern of a pseudo-dilated common bile duct caused by either a redundant or folded neck of the gallbladder. Recognition of this entity as well as the use of real-time ultrasound equipment should minimize false-positive diagnoses of extrahepatic bile duct dilatation.