Which of the following statement(s) about gallstone ileus is/are not true?

C. The usual fistula underlying the problem is between the gallbladder and the ileum

DISCUSSION: It is true that gallstone ileus occurs mostly in elderly women and should always be suspect when small bowel obstruction presents in this age group. The great majority of cases of gallstone ileus are preceded by a spontaneous fistula occurring between the gallbladder and duodenum, allowing gallstones to enter the intestinal tract, which can potentially block the terminal ileum. Finding air within the biliary tree should always arouse suspicion of the possibility of this diagnosis when it is associated with a radiographic pattern of small bowel obstruction. The initial part of the operative approach to this disease is to relieve the bowel obstruction by performing an enterotomy just proximal to the point of obstruction to remove the stone. Where possible, definitive repair of the fistula should be undertaken to avoid recurrent obstruction and to obviate the possible recurring complications of cholangitis. Percutaneous drainage of bile collections combined with endoscopic papillotomy may be sufficient treatment for external and internal biliary fistulas but is never an allowable approach in the presence of gallstone ileus with small bowel obstruction. Relief of the obstruction is mandated in this setting.