Duodenal Diverticulum Draining Ampulla of Vater

This patient had biliary obstruction from a Klatskin tumour. On inserting a biliary drain from the left hepatic ductal system into the duodenum, the common bile duct was noted to drain into a duodenal diverticulum. On this image, it can be seen by following the course of the biliary catheter into the diverticulum.
Duodenal diverticula are usually acquired pseudodiverticula and most arise along the concave border of the second or third parts of the duodenum. 75% arise within 2 cm of the ampulla of Vater and it is not uncommon for the ampulla to empty into the diverticulum.
Insertion of the ampulla into a duodenal diverticulum is clinically important for several reasons. Firstly, it may cause difficulty with retrograde cannulation of ampulla during ERCP, or antegrade cannulation into the main duodenal lumen during percutaneous biliary intervention. Secondly, it is important to recognise if duodenal surgery is contemplated. Thirdly, stasis of duodenal contents within the diverticulum may cause partial obstruction of ampullary drainage, which is believed to predispose to biliary calculi, cholangitis and pancreatitis.
References:
1. Medcyclopaedia.com
2. Schulze K. Review of duodenal diverticula, Radiology, 1992;183:554
Credit: Dr Donna D'Souza
http://www.radpod.org