Gallstone ileus

Gallstone ileus is an overall uncommon cause of a small bowel obstruction (SBO). It occurs when a gallstone passes into the small bowel and usually impacts at the iliocaecal valve. Usually passage into small bowel is by erosion from the gallbladder into the duodenum. 

Demographics and clinical presentation

Although overall gallstone ileus is an uncommon cause of small bowel obstruction, in the elderly is not uncommon, and accounts for up to 25% of non-strangulated bowel obstructions ¹. As is the case with cholelithiasis, women are more frequently affected.

Radiographic features

Most frequently, stones impact in the distal ileum, although other locations are also encountered ⁵:

• terminal ileum : most common
• proximal ileum
• jejunum
• colon
• duodenum / stomach : leading to gastric outlet obstruction (Bouveret's syndrome)

X-ray

Classically the findings on abdominal xrays are a small bowel obstruction, gas within the biliary tree and a gallstone (usually in the right iliac fossa). This is known as Rigler's triad. 

CT

Appearances are those of Rigler's triad, better seen than on plain films. Care must be taken in finding the gallstone, as only a minority (12.5%) are calcified, and density may be very similar to bowel content ¹. The presence of bulging of the bowel just prior to the transition point is often seen. Typically stones are a number of centimetres across (2-3cm).

Additionally, the site of fistulization is often visible.

Note should be made of free fluid, free gas, portal venous gas or mural gas, as signs of more advanced disease and poorer prognosis.

Treatment and prognosis

Due to the demographics of the population affected (elderly) this condition continues to have a high mortality (16-30%) ^1-2

Surgery is definitive, with removal of the stone (enterolithotomy) and repair of the choledochoenteric fistula, accompanied by a cholecystectomy.

Differential diagnosis

The differential is essentially that of each component of Rigler's triad.

• lower abdominal / pelvic calcification
• small bowel obstruction (other causes)
• pneumobilia

Etymology

The entity was first described in 1654 ^3,4 by:

• Bartholin (1616-1680), a Danish physician, naturalist, physiologist and anatomist