An 85-year-old woman with dementia and multiple comorbidities had a 4-day history of vomiting. Six months prior to admission, she had cholecystitis that was treated with a cholecystostomy tube. The tube was subsequently removed when her symptoms resolved. On examination, she was afebrile with normal vital signs. She was alert but confused and had a soft, nontender, and nondistended abdomen without rebound or guarding. She had a white blood cell count of 10 500/μL, a normal amylase level, a normal lipase level, and normal liver function test results. The abdominal radiograph showed a dilated small bowel, minimal colonic air, and no obvious cause for the small-bowel dilation. A computed tomographic scan showed pneumobilia, collapsed gallbladder, dilated small bowel, and a 3 × 4-cm gallstone in the small bowel (Figure 1). The gallstone had not been visible on the abdominal radiographs. The patient was diagnosed with gallstone ileus and taken to the operating room, where she underwent a laparotomy (Figure 2).