Annular Pancreas

Annular pancreas is when tissue from the head of the pancreas surrounds the descending duodenum resulting in obstruction. 

Suspect annular pancreas in an infant with bilious vomiting after feeding and a double bubble sign on abdominal x-ray (air in the stomach and duodenum proximal to the obstruction). 

Annular pancreas can also present in adulthood and with similar symptoms. This is less common. 

Laboratory testing in patients with annular pancreas reveals: hypochloremic metabolic alkalosis and hypokalemia.

Labs: low K, low Cl, high pH. 

Abdominal x-ray: air in the stomach and proximal duodenum (double bubble sign) with little to no air in the rest of the bowel. 

Upper GI contrast x-ray study: narrowed duodenum at location of obstruction with proximal dilation.

ERCP: confirms the diagnosis and shows duodenum surrounded by pancreatic tissue. 

Surgery to bypass the obstruction