Although its anatomy varies between individuals, from the duodenal aspect, the major ampulla (dashed circle) is usually readily visible. The accessory ampulla (probe), typically located about 2 cm proximal and slightly anterior to the papilla of Vater, appears as a nodule and can be mistaken for a polyp endoscopically. It is important to examine this area for any mucosal nodularities or irregularities or thickening, as paraduodenal pancreatitis often manifests in this region with variable, often subtle, abnormalities.