The clinical picture of gallstone ileus includes which of the following?

A. Air in the biliary tree.

B. Small bowel obstruction.

C. A stone at the site of obstruction.

E. Associated bouts of cholangitis. 

DISCUSSION: An antecedent biliary-enteric fistula is necessary to allow stone migration into the intestinal tract, and this results in air entering the biliary tree (pneumobilia). It also allows contamination of the bile ducts with intestinal bacteria, which in fact occurs in only a minority of such cases. The stone obstructs the narrower distal bowel, producing small bowel obstruction. Such a stone, if opaque, can be seen on plain radiography and, if not, can be appreciated by sonography. Stools are not acholic, since the cholecystoenteric fistula allows bile access to the intestinal lumen.