Gallstone ileus is a rare condition that can develop following inflammation of the gall bladder when a gallstone entering the bowel causes gastrointestinal obstruction. It occurs mainly in the elderly; the advanced age and comorbidities make the management of the disease challenging.
Gallstone ileus is the consequence of a gallstone entering the gastrointestinal tract (GIT). In most cases, the stone passes through a fistula formed between the gallbladder and the duodenum . This often follows signs of biliary problems, for example, cholecystitis, with the inflammation contributing to the formation of the fistula.
The stone may pass through the GIT or may be expelled with vomit; alternatively, it may cause partial or complete obstruction, the terminal ileum being the most usual location of impaction. The presentation is of general small bowel obstruction: nausea, vomiting, abdominal pain, and distention. The signs may disappear and reappear since the stone may “tumble” and change position. As the stone migrates towards a distal location, the vomit changes from a light gastric character to a darker shade.
Gallstone ileus constitutes less than 0.1 percent of cases with mechanical obstruction of the GI tract . However, a quarter of the cases with small bowel obstruction in the older population (above 65) can be attributed to gallstone ileus .
A rare form of gallstone ileus, called Bouveret syndrome , arises when a gallstone is lodged in the duodenum and causes gastric outlet obstruction. Therefore, pain tends to occur around the epigastrium and right hypochondrium, and the stomach is distended.
The disease occurs mainly in elderly females. The mean age of patients has been reported as 68.6 years for Bouveret syndrome , and 77 years for gallstone ileus in general . The nonspecific nature of symptoms makes diagnosis problematic, and the advanced age and debility of the patients makes the management of the condition difficult.
The intermittent and nonspecific nature of the symptoms delays the diagnosis. Often days pass after the onset of problems until the patient visits a healthcare facility , and the diagnosis may be delayed. The accuracy of diagnosis before surgery is not high (43-73%) . Laboratory studies may show electrolyte and acid-base imbalances.
Plain radiographs have been found useful for diagnosing gallstone ileus. Originally, four characteristic radiological signs that strongly indicate gallstone ileus were described by Rigler et al . Three of the signs are referred to as the Rigler triad: partial or complete intestinal obstruction, pneumobilia, and ectopic gallstone. Observing two of the three in a patient is considered pathognomonic. However, the signs of the Rigler triad are observed variably , with less than half of the cases showing signs of the triad  . Plain radiographs cannot detect the gallstones themselves because the density of the stones is poor. Gallstones, as well as pneumobilia are recognized by ultrasound , but the interpretation of the images may not be unequivocal . Combining results from plain radiography with those from ultrasound improves the diagnosis prior to surgery .
Computed tomography (CT) is regarded as the best method for the detection of signs of the Rigler triad . In one study, CT found signs of the Rigler triad in 77% of patients with gallstone ileus, whereas radiography identified the triad in only 14.8% of the cases . CT can diagnose gallstone ileus with a sensitivity of up to 93% .
Magnetic resonance cholangiopancreatography is useful for locating gallstones that are not detectable by other methods. Magnetic resonance may be the method of choice for examining patients who are unable to swallow oral contrast material.