Duodenal Diverticulum

Diverticulum of the duodenum is an acquired pouch-like herniation in the wall (mucosa and muscularis mucosa) of the duodenum. It is far less common than colonic diverticula (1). The actual cause is unknown; however it is believed to develop as result of elevated segmental pressure and abnormal peristalsis . Majority of duodenal diverticula are asymptomatic, with complication in minority of patients, occurs more commonly in women. Patient may present with abdominal pain, gastrointestinal bleeding, perforation, obstruction and diverticulitis (2). It is incidentally detected during imaging or endoscopic investigations. Doudenal diverticula are most commonly seen along the medial border of the descending duodenum (mainly 3rd and 4th portion) within 2.0 cm of the ampulla of Vater (1). Duodenal diverticulum is easily recognized on cross-sectional imaging such as CT or MRI when it contains both gas and fluid content. It appears inapparent when contents are purely cystic (2). CT scan often shows discrete collection of gas with contrast seen along the medial border at the junction of second and third part of duodenum. MRI is quite convincing in showing small air fluid levels or gas within diverticula. The gas is seen as hypointense while fluid is seen as high signal intensity on T2 weighted sequence as shown in our case. Magnetic resonance cholangiopancreatography (MRCP) sometimes helps in proving a road map in case the papilla is being obstructed and difficult to cannulate on ERCP. Complication may include hemorrhage, biliary sludge, cholidocholithiasis as a result of compression of CBD by large diverticulum. The main differential diagnosis which can be confused with duodenal diverticulum is the cystic tumor of pancreas due to their proximity to the pancreatic head (3). MRCP with negative contrast with bright signal suppression of fluid within helps excluding duodenal diverticulum from cystic pancreatic tumors. Otherwise air-fluid level in the diverticular sac and the communication between the duodenum and diverticulum is helpful in distinguishing duodenal diverticula from pancreatic cystic lesions. Only about 1 percent of duodenal diverticula warrant surgery. Surgical management is required for persistent symptoms and complications.