Abdominal computed tomography (CT) scan with intravenous and oral contrast enhancement. Labels on the figure are as follows. 1: Contrast material in the lumen of the stomach. 2: Pyloric sphincter. 3: Contrast material in the lumen of the duodenal bulb. 4: Gallstone impacted in the lumen of the third part of the duodenum. *: Contrast material in the lumen of the gallbladder (notice thickening of the wall of the gallbladder and communication with the duodenal bulb). #: Contrast material in the lumen of the descending duodenum.