Article Sections

Introduction

Annular pancreas is a rare congenital anomaly in which a ring of pancreatic tissue encircles the duodenum.  Patients with annular pancreas are often asymptomatic but may have signs of duodenal obstruction (eg, abdominal distension, emesis).

Pathophysiology and risk factors

Pancreatic development is a complex process that involves the formation, rotation, and fusion of the dorsal and ventral pancreatic buds, which are foregut derivatives ( Figure 1).  The ventral pancreatic bud gives rise to the uncinate process of the pancreatic head and the main pancreatic duct ( Figure 2).  The dorsal pancreatic bud gives rise to the remainder of the pancreatic head as well as the tail and body.

Normally, the ventral pancreatic bud rotates behind the duodenum and fuses with the dorsal pancreatic bud by the 8th week of gestation.  Annular pancreas develops when the ventral pancreatic bud fails to rotate completely (

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