Solution: Bouveret's syndrome is a rare process where there is impaction of a gallstone proximally in the duodenal bulb or pylorus, resulting in obstruction. It is on the spectrum of a gallstone ileus and represents 1-3% of those cases. Rigler's triad is described as the three findings associated with gallstone ileus, bowel obstruction, pneumobilia, and the obstructing gallstone. In this case, you can see the stone and pneumobilia on the pain film and the filling defect in the duodenal bulb, which is obstructing gastric outflow. Here are some CT images confirming the findings.