Teaching Case

A 65-year-old lady presented with abdominal pain. The symptoms started 24 hours ago and gradually got worse leading to A&E presentation.
She had a medical history of breast cancer treatment with curative intent for stage 1 diagnosis. There was no other significant past medical history.

Plain abdominal film was performed in A&E, which demonstrated mild dilatation of small bowel loops (Fig. 1), and the patient was admitted for observation. A nasogastric tube was passed to relieve obstruction (Fig. 2).
Overnight the symptoms got worse and a CT scan was performed, which demonstrated pneumobilia (Fig. 2). Small bowel loops were dilated in the upper abdomen (Fig. 3) up to a transition point in the right iliac fossa (Fig. 4) and no gall bladder was evident (Fig. 2).

Small bowel obstruction due to gallstones is seen in less than 5% in young patients but is seen in up to 25% in patients over 65 years of age [1]. As in our case, asymptomatic patients are usually managed conservatively with NG tube and symptomatic relief (Fig. 2). The CT diagnosis was small gallstone ileus with characteristic findings of Rigler’s triad, i.e. distended small bowel loops, pneumobilia due to the cholecysto-enteric fistula (Fig. 3) and an ectopic gallstone (Fig. 4).
The usual presentation is a known history of gallstones. Conservative management is usually successful but occasionally progresses to gallstone ileus, especially in the elderly population [3]. The stone can rarely move up causing gastric outlet obstruction or Bouveret’s syndrome [2]. The gallstone usually moves down the fistulous tract and leads to mechanical obstruction at ileocaecal junction (Fig. 4).
This case is interesting as it demonstrates the same findings on plain film and CT scan, thus demonstrating the evolution of a disease process over time. The plain film for lumbar spine from 2013 (Fig. 7) shows the gallstone in the typical location of the gall bladder fossa. The plain film of the abdomen from 2017 (Fig. 1) demonstrates that the gallstone has moved to the upper abdomen at L4 level together with pneumobilia, i.e. Rigler triad on plain film. The CT scan performed after a period of observation demonstrates that the stone has moved from the proximal small bowel to the distal small bowel near the ileocolic junction over a period of few hours (Fig. 4).
This case also emphasises the golden rule of comparison with previous imaging (Fig. 4 vs Fig. 6). Generally, it is assumed that the ectopic stone is a gallstone due to pneumobilia of fistulous communication. In this case one can clearly confirm this to be the case in both plain films (Fig. 1 vs Fig. 7) and CT scan which demonstrated stones in the gall bladder in earlier films and movement of the same solitary stone in the most recent study (Fig. 3 vs Fig. 6).
For investigation of acute abdomen, plain films and ultrasound have gone out of favour over time due to the much superior ability of CT scan to demonstrate pathology such as free air and traces of free fluid. With plain films for acute abdomen no longer in favour (largely replaced by CT scan), it is exceedingly difficult to find a case demonstrating all the findings in plain film and confirmed by CT scan.

Written patient consent for this case was waived by the Editorial Board. Patient data may have been modified to ensure patient anonymity.