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Annular Pancreas

General Considerations

  • Rare, congenital anomaly that may not become apparent until adult life
  • Pancreas completely (or sometimes incompletely) encircles 2nd portion of duodenum occasionally obstructing more proximal duodenum
  • More commonly affects males
  • Pancreas develops from two analogues
    • Larger is dorsal bud which forms body and tail of gland
    • Ventral bud is smaller and forms head of gland as well as parts of the hepatic duct and gallbladder
    • Annular pancreas is believed to develop as a result of abnormalities in migration of the ventral bud such that the two buds join to encircle the duodenum
  • Pancreatic duct from the annular portion may drain into the main pancreatic duct or directly into the duodenum


Clinical Findings

  • Frequently asymptomatic
  • May present either in infancy or, more commonly, 4th-5th decade of life
    • In newborn, duodenal obstruction with bilious vomiting may be present
      • May be associated with duodenal stenosis or atresia
      • There is a 50% association with other congenital anomalies of involving the heart, trachea and esophagus and malrotation of the intestine
  • In adult, there may be
    • Upper abdominal colicky pain
    • Postprandial fullness
    • Vomiting
    • Higher incidence of pancreatitis
    • Peptic ulcers may develop

Imaging Findings

  • In newborn, there may be a double bubble sign from dilatation of the stomach and first portion of the duodenum
  • In, adult the diagnosis is usually suggested first by CT and can be confirmed with MRCP (magnetic resonance cholangiopancreatography) or ERCP (endoscopic retrograde cholangiopancreatography)
  • UGI series    
    • May show extrinsic compression on both lateral and medial walls of the  2nd portion of duodenum
  • CT
    • May be mistaken for thickening of the duodenal wall

  • On MRCP or ERCP, the duct of the annular pancreas usually originates anterior to the duodenum

    sweeps posteriorly and opens into the main pancreatic duct or ampulla

Differential Diagnosis

  • Pancreatic divisum
    • Failure of the dorsal and ventral pancreatic ducts to fuse resulting in the majority of secretions exiting via the accessory pancreatic duct of Santorini
  • Pancreatic neoplasms
  • Duplication cyst of the duodenum
  • Duodenal atresia


  • Symptomatic newborns require surgical intervention
  • Most symptomatic adults will undergo a surgical bypass of the duodenal obstruction


  • Pancreatitis
  • Peptic ulcer disease


  • In newborn, except for the possible presence of other congenital anomalies, surgery is usually successful
  • Surgery should be completely successful in an adult

Annular Pancreas

Annular Pancreas. Three, contrast-enhanced axial CT images of the abdomen demonstrate the body and head of the pancreas (light blue arrows) completely encircling, but not obstructing, the duodenal loop (red *)
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Annular pancreas in the adult. W Lloyd-Jones, J C Mountain, and K W Warren; Ann Surg. 1972 August; 176(2): 163–170.


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