GI Radiology > Pancreas > Congenital > Annulae

Annular Pancreas

   Annular pancreas results from a band of pancreatic parenchyma that encircles a section of the second part of the duodenum.  The embryologic anomaly is secondary to the malrotation of the ventral bud, which wraps around the duodenum to fuse with the dorsal bud.  This malformation can be isolated or can be accompanied by a digestive tract malrotation or atresia.  Its frequency is also increased by Trisomy 21.

Embryological Development of Annular Pancreas

Shirkhoda et al.: Anomalies and anatomic varients of the pancreas. In Gore & Levine, Textbook of Gastrointestinal Radiology, 2n Ed. Phila: W. B. Saunders Co., 2000, p 1761


   The clinical consequences of annular pancreas depend on the degree of duodenal obstruction.  In cases of complete obstruction, the diagnosis is readily evident in the neonate.  Plain films reveal two asymmetrical air-fluid levels, one gastric, the other duodenal, with little distal bowel gas.  This is the "double bubble" sign.  The diagnosis can be suggested by prenatal US, which would demonstrate the two constant liquid-containing abdominal structures, possibly accompanied by hydroamnios.  This anomaly may present later, and into adulthood, as partial duodenal obstruction or pancreatitis.  The treatment of significant obstruction is always surgical.

Findings of Annular Pancreas

Pancreatic duct of Santorini folding around the duodenum.
Single contrast duodenal examination revealing annular excentric stricture.
"Double bubble" sign:
-Thin arrow: dialated stomach
-Thick arrow: dialated proximal duodenum

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