From the Department of Radiology, Baylor University Medical Center, Dallas, Texas.

Corresponding author: Robert M. Branstetter, MD, Department of Radiology, Baylor University Medical Center, 3500 Gaston Avenue, Dallas, Texas 75246.

For diagnosis and discussion, see the following page.

DIAGNOSIS: Gallstone ileus.

Gallstone ileus is an intestinal obstruction produced by 1 or more gallstones becoming impacted within the lumen of the bowel (1). The condition is a well-known but uncommon complication of biliary stone disease, accounting for only 2% of all cases of intestinal obstruction. Gallstone ileus is, however, more common in the elderly and accounts for approximately 25% of all cases of intestinal obstruction in patients >70 years of age (2, 3). With life expectancy increasing, the condition is being encountered more frequently (1).

Gallstones usually enter the intestinal lumen through a cholecystenteric fistula, and 68% of these are between the gallbladder and the duodenum (1). A history of prior biliary tract disease is present in almost half of the patients with gallstone ileus.

Abdominal pain is a prominent symptom, and associated illnesses such as diabetes and cardiovascular disease are common (2). However, the characteristic features of intestinal obstruction are found in only 50% to 70% of patients. This is believed to be because as the gallstone “tumbles” through the gastrointestinal tract, it impacts and disimpacts, producing intermittent mechanical obstruction. Consequently, abdominal distention is intermittent, and patients frequently have diarrhea. The relief of symptoms that occurs when the stone disimpacts may suggest an incorrect diagnosis of gastroenteritis (1). The stone eventually becomes completely impacted as the diameter of the small bowel decreases distally and the stone gradually enlarges secondary to sediment accumulation from intestinal contents (4). Because the ileum is the narrowest part of the bowel, it is the most frequent site of stone impaction (>60% of cases). Other sites of obstruction are the jejunum (16%), stomach (14%), colon (4%), and duodenum (3%). Gastric outlet obstruction, or Bouveret's syndrome, occurs when the gallstone lodges in the duodenal bulb (1).

Because the clinical and radiological diagnosis of gallstone ileus is often difficult (3), the condition is associated with high rates of morbidity and mortality. In some series, death is reported in up to 20% of patients. This outcome is probably related to the fact that the condition occurs in an older age group that frequently has significant coexistent medical problems (2).

The classic radiographic signs of gallstone ileus, described in 1941 by Rigler et al, are pneumobilia, mechanical small-bowel obstruction, and the presence of a new stone or changed position of a previously identified stone (2). These classic signs, however, are infrequently seen on the initial abdominal radiograph (3). Furthermore, the radiological findings on plain abdominal radiographs may be subtle and can be easily missed.

The characteristic findings of gallstone ileus (Rigler's triad) are easily identified on CT (2), and these findings are all present in the current case. As shown in Figure 4 and Figure 5, CT can demonstrate the intraluminal gallstone even when the stone is not extensively calcified (4). Abdominal ultrasound is also reported to be useful in establishing the diagnosis (3).

When abdominal radiography reveals the characteristic signs of small-bowel obstruction, CT is useful for excluding complications (e.g., strangulation) when nonsurgical treatment is considered. CT findings can reduce delays in accurate diagnosis, influence decisions about conservative or surgical intervention, and identify serious complications, thus reducing morbidity and mortality (4). When unexplained bowel obstruction is present, particularly in the elderly, the early use of CT is strongly recommended (2).

The best surgical procedure for patients with gallstone ileus has been debated. Current reports favor enterolithotomy only with definitive biliary surgery performed later if symptoms persist. Alternatively, a procedure that combines stone extraction and cholecystectomy may be done. Advocates of the combined procedure contend that it prevents recurrent gallstone ileus, cholangitis, and gallbladder carcinoma--complications that occur in nearly one third of patients who undergo enterolithotomy only (2).

In the current case, surgery revealed a cholecystoileal fistula approximately 35 cm from the ileocecal valve. Multiple large gallstones were found in the ileum slightly distal to the fistula. A short segment of ileum containing the gallstones was resected, and a cholecystectomy was performed.

1. Lobo DN, Jobling JC, Balfour TW. Gallstone ileus: diagnostic pitfalls and therapeutic successes. J Clin Gastroenterol 2000;30:72-76.
2. Seal EC, Creagh MF, Finch PJ. Gallstone ileus: a new role for abdominal computed tomography. Postgrad Med J 1995;71:313-315.
3. Loren I, Lasson A, Nilsson A, Nilsson P, Nirhov N. Gallstone ileus demonstrated by CT. J Comput Assist Tomogr 1994;18:262-265.
4. Swift SE, Spencer JA. Gallstone ileus: CT findings. Clin Radiol 1998;53:451-454.