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  • • Ring of pancreatic tissue from the head of the pancreas surrounds the descending duodenum, leading to obstruction, presenting either in infancy or adulthood

    • Vomitus is bilious if obstruction is distal to the ampulla of Vater

    • Air in the stomach and duodenum proximal to the obstruction on abdominal x-ray (double bubble sign)

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Epidemiology

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  • • Rare congenital condition in which a ring of pancreatic tissue from the head of the pancreas surrounds the descending duodenum

    • The abnormality usually presents in infancy as duodenal obstruction with postprandial vomiting

    • There is bile in the vomitus if the constriction is distal to the entrance of the common bile duct

    • Occasionally, annular pancreas will present in adults with similar symptoms

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Symptoms and Signs

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  • • Upper GI obstruction

    • Vomiting

    • Upper GI bleeding

    • Epigastric pain

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Laboratory Findings

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  • • Hypochloremic metabolic alkalosis

    • Hypokalemia

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Imaging Findings

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  • Abdominal x-ray: Dilated stomach and proximal duodenum (double bubble sign) and little or no air in the rest of the small bowel

    Upper GI contrast radiography: Narrowing of the duodenum where it is encircled by the pancreatic head, with proximal dilation

    ERCP: Pancreatic duct in head of pancreas encircling duodenum

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  • • Signs and symptoms of upper GI obstruction should prompt radiographic imaging, which may suggest duodenal obstruction

    • Always consider annular pancreas as a cause of duodenal obstruction

    • May cause peptic ulcer disease or chronic pancreatitis in an adult

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Rule Out

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  • • Other causes of duodenal obstruction

    • -Duodenal tumors

      -Pancreatic head masses

      -Duodenal atresia (infant)

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  • • Abdominal x-ray

    • Upper GI contrast radiography

    • ERCP confirms the diagnosis but is not necessary

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When to Admit

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  • • All symptomatic cases

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  • • Correction of fluids and electrolytes

    • The obstructed segment should be bypassed by a duodenojejunostomy

    • The obstructing pancreas should not be resected; high risk for pancreatic fistula

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Surgery

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Indications

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  • • All cases in children

    • All symptomatic cases in adults

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Complications

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  • • Chronic pancreatitis

    • Peptic ulcer disease

    • Obstruction

    • Bleeding

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Prognosis

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  • • Excellent after surgical bypass of obstruction

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References

Chen YC et al. Symptomatic adult annular pancreas. J Clin Gastroenterol. 2003;36:446.  [PubMed: 12702992]
McCollum MO et al. Annular pancreas and duodenal stenosis. J Pediatr Surg. 2002;37:1776.  [PubMed: 12483656]

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