Case reportA 95-year-old woman with a virgin abdomen presentedto the Emergency Department (ED) with a 1 week his-tory of vomiting, absolute constipation and generalisedabdominal pain. Physical examination revealed tenderabdominal distension with hyperactive bowel sounds andno hernias. Abdominal plain film radiograph (PFR)showed dilated small bowel loops without an obvioustransition point or a radiologically apparent cause(Fig. 1a). Abdominal computed tomography scan (CTscan) revealed a cholecysto-duodenal fistula, pneumobiliaand dilated small bowel loops proximal to a 1 cmdiameter calcified intra-luminal structure in the distalileum consistent with an ectopic gallstone (Fig. 1b, c).The patient underwent mini-laparotomy through a rightiliac fossa incision, enterolithotomy and extraction of a2.5 cm diameter gallstone (Fig. 1d), from which sherecovered uneventfully.DiscussionGallstone ileus (GSI) accounts for 1–3% of cases of smallbowel obstruction (SBO) in the general population but ismore common in those patients over the age of 65 where itis responsible for up to 25% of cases of non-strangulatedSBO [1]. While PFR is likely to confirm the presence ofdilated bowel, it is rarely useful in diagnosing GSI sinceonly 10% of gallstones are calcified and thus visible asradio-opaque structures [2]. Ultrasound is purported tohave greater than 95% specificity and sensitivity indetecting gallstones within the gallbladder, but is of limiteduse in GSI due to gaseous distension of the bowel [2]. ACT scan is more reliable than PFR in detecting the classicalradiological manifestations of GSI described by Rigler’striad (pneumobilia, intestinal obstruction and visualizationof a gallstone within the bowel), but it too will fail to detecta non-calcified gallstone [1, 2]. Although gallstones with adiameter of less than 2.5 cm may pass spontaneously, a CTscan will not accurately identify the true size of a partiallycalcified gallstone (as in this case), and thus should not beused to determine the appropriateness of surgery.Enterolithotomy alone is appropriate as primary treat-ment because remaining gallstones pass spontaneouslywithout causing symptoms in 80–90% of cases and closureof the fistulous tract occurs spontaneously in the absence ofpersisting cholelithiasis. However, given that 10% ofpatients require reoperation for persistent biliary symptoms(such as recurrent gallstone ileus, cholecystitis and cho-langitis) others advocate a definitive procedure (entero-lithotomy, cholecystectomy and repair of biliary-entericfistula), particularly in patients with minimal co-morbidconditions [1].Bowel obstructions are responsible for 20% of surgicaladmissions with acute abdominal pain and 80% of thesecases are due to small bowel pathology [3]. While the exactetiology of small bowel obstruction is often impossible todetermine in the ED, it is prudent to involve the surgicalservice early in the care of such patients.