Location

Type I

Duodenal obstruction proximal to the major papilla

Type II

Duodenal obstruction involving the major papilla

Type III

Duodenal obstruction distal to the major papilla

Timing

Group 1

Biliary obstruction occurring before the onset of duodenal obstruction

Group 2

Biliary and duodenal obstruction occurring simultaneously

Group 3

Biliary obstruction occurring after the onset of duodenal obstruction