56-year-old female patient presented to the Emergency Department with acute generalised abdominal pain and associated abdominal distention and vomiting. Patient also complained of a three month history of intermittent right upper quadrant pain for which she had been scheduled to undergo an abdominal ultrasound as an outpatient.
Upon presentation to the Emergency Department, the patient underwent a plain film abdomen (Fig. 1) that showed dilated loops of small bowel consistent with obstruction and an incidental 1cm radio-opacity in the right iliac fossa consistent with a fecalith. There was a larger less radiopaque object projected over the left iliac fossa that was not discovered on initial inspection. The patient went on the have a CT abdomen that showed Rigler's Triad of pneumobilia, ectopic gallstone, and small bowel obstruction. Figures 2 and 3 show air within the biliary tree and gallbladder. Figure 4 and 5 shows an ectopic gallstone obstructing the small bowel. Figure 6 shows a coronal view of the small bowel obstruction with collapsed distal colon. Finally, figure 7 shows a coronal CT view of the distracting fecalith that was originally seen on PFA.
A) Gallstone ileus is most common between 65-75 years old and like all gallstones has a much higher prevalence in the female population by a ratio of 5:1. Gallstone Ileus accounts for only 0.5% of all gallstone related presentation and only 1-2% of all mechanical small bowel obstruction. However, it carries a significant morbidity and mortality rate of 12-18% [1, 3]. The patient presenting with gallstone ileus, as in this case, is usually known to have a background of recurrent cholecystitis. This leads to inflammation and adhesions which puts pressure on the gallbladder wall until it eventually erodes and forms a fistula. The most common site of fistula formation is cholecystoduodenal accounting for 60%. Once the gallstone has entered the small bowel it most commonly works its way to the terminal ileum before causing obstruction. However, obstruction can also occur at the ligament of treitz in the jejunum in about 30% of cases or in the colon in about 2.5% of cases .
B) Biliary symptoms combined with signs of obstruction are the classic presentation. Tumbling phenomenon has also been described, whereby the symptoms of obstruction resolve as the stone moves more distally through the GI tract. It is also possible for the stone to pass completely through the GI tract if it is less than 2cm .
C) Plain film abdomen imaging in this case was enough to make a definitive diagnosis of gallstone ileus. However, the gallstone, although present on the Plain film abdomen was not originally seen until looked at after the patient underwent a CT. In most cases, the gallstone is likely to be present in the right iliac fossa where in this Plain film abdomen a fecalith was distracting the viewer from the discrete gallstone in the left iliac fossa. On CT imaging, it can also be easy to miss the gallstone as only a minority of them are calcified and therefore may have similar density to the small bowel .
D) As shown in figure 8, a simple enterotomy is the treatment of choice and an urgent fistula repair should only be attempted in select cases as it greatly increases the risk of complication .
E) A complete history and examination combined with a plain film abdomen is enough to definitively diagnose gallstone ileus.
Differential Diagnosis List
Dropped gallstone secondary to laparoscopic cholecystectomy