This common duct usually features a dilation ("ampulla").

The common duct then opens medially into the descending part of the duodenum at the major duodenal papilla.

[1] The ampulla of Vater is an important landmark halfway along the second part of the duodenum marking the transition from foregut to midgut.

[1] Thomas' sign is the production of silver stools and can be indicative of cancer of the Ampulla of Vater.

The ampulla of Vater is the site of tumors, often with a threatening prognosis and difficult surgical treatment.