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Annular Pancreas
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Annular Pancreas

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ICD-10

Q45.1

Specialty

Gastroenterology

Onset

Chronic

Reviewed

July 2026
On This Page

Overview

  • May be complete or incomplete depending on how much of the duodenum is encircled.
  • Many individuals are asymptomatic, while others present in infancy or adulthood.
  • Symptoms are mainly due to duodenal obstruction and may include feeding difficulties and vomiting in neonates, or abdominal pain, nausea, vomiting, postprandial fullness, and pancreatitis in adults.
  • Asymptomatic patients usually require no treatment, whereas symptomatic cases are typically managed with surgical bypass procedures (e.g., duodenoduodenostomy).

Etiology & Risk Factors

Etiology

  • Congenital condition caused by defective migration and malrotation of the ventral pancreatic bud during embryonic development.
  • This abnormal development forms a complete or partial ring of pancreatic tissue around the second part of the duodenum.

Risk Factors / Associated Conditions

  • Annular pancreas is commonly associated with:
  • Down syndrome
  • Congenital heart defects
  • Intestinal malrotation
  • Duodenal atresia
  • Meckel diverticulum
  • There are no known acquired risk factors because annular pancreas is a congenital embryologic anomaly.

Pathophysiology

Defective migration and malrotation of the ventral pancreatic bud (embryonic development) → Ring of pancreatic tissue forms around the second part of the duodenum → Compression/narrowing of the duodenum → Partial or complete duodenal obstruction → Impaired passage of gastric contents → Vomiting, feeding difficulty, abdominal distention (or abdominal pain/postprandial fullness in adults) → May also lead to pancreatitis and biliary obstruction

Clinical Presentation

  • Many patients are asymptomatic. Symptoms depend on the age at presentation.

    Prenatal

    • Polyhydramnios

    Neonates

    • Feeding difficulties
    • Abdominal distention
    • Nonbilious or bilious vomiting

    Adults

    • Abdominal pain
    • Nausea and/or vomiting
    • Postprandial fullness
    • Symptoms of pancreatitis
    • Peptic ulcer disease
    • Jaundice (uncommon)
Annular Pancreas Overview
Annular Pancreas Overview

History Taking

Ask about:

    • When did the symptoms start?
    • Is there vomiting? Is it bilious or nonbilious?
    • Does vomiting occur after feeding or meals?
    • Is there feeding difficulty or poor weight gain? (infants)
    • Is there abdominal pain? Is it related to meals?
    • Do you feel full quickly after eating (postprandial fullness)?
    • Have you had recurrent episodes of pancreatitis?
    • Have you noticed yellowing of the eyes/skin (jaundice)?
    • Is there a history of Down syndrome or other congenital anomalies?

Physical Examination

  • General appearance: May appear well if asymptomatic.
  • Signs of dehydration: Dry mucous membranes, sunken eyes, tachycardia (from persistent vomiting).
  • Abdominal distention: Especially in neonates with duodenal obstruction.
  • Epigastric tenderness: If associated with acute pancreatitis.
  • Visible vomiting (bilious or nonbilious), especially after feeds in infants.
  • Poor weight gain/failure to thrive: In infants with chronic obstruction.
  • Jaundice: May be present if there is biliary obstruction (uncommon).
  • Signs of malnutrition: In prolonged or severe cases.

Investigations

Laboratory tests

  • Usually not diagnostic
  • Serum amylase/lipase if pancreatitis is suspected
  • Liver function tests (bilirubin, ALP) if jaundice or biliary obstruction is suspected

Imaging (mainstay of diagnosis)

  • Prenatal ultrasound: Polyhydramnios and features of duodenal obstruction
  • Abdominal X-ray: Double bubble sign (duodenal obstruction)
  • CT scan or MRI (best diagnostic imaging):
    • Pancreatic tissue completely or partially encircling the second part of the duodenum
    • Duodenal narrowing/thickening
    • Proximal duodenal dilatation

diagnostic finding

  • Ring (complete or partial) of pancreatic tissue surrounding the second part of the duodenum on cross-sectional imaging.

Diagnosis

-Diagnosis is based on :

  • Diagnosis is based on clinical suspicion plus imaging findings.

Diagnostic criteria

  • Symptoms of duodenal obstruction (or incidental finding in asymptomatic patients)

Cross-sectional imaging (CT or MRI) showing:

  • Complete or partial ring of pancreatic tissue surrounding the second part of the duodenum (diagnostic finding)
  • Duodenal narrowing/thickening
  • Proximal duodenal dilatation
  • Prenatal ultrasound or abdominal X-ray may support the diagnosis by showing a double bubble sign (duodenal obstruction).
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Related Topics

Management

 1. Initial/Supportive Management

  • Keep NPO (nil by mouth) if there is significant obstruction.
  • IV fluids to correct dehydration and electrolyte imbalance.
  • Nasogastric (NG) tube for gastric decompression if persistent vomiting or obstruction.
  • Treat associated complications (e.g., acute pancreatitis or biliary obstruction) as indicated.

2. Definitive Management

  • Asymptomatic patients: No treatment required; observation and follow-up.
  • Symptomatic patients: Surgical intervention is recommended.

3. Surgery (Treatment of Choice)

  • Duodenoduodenostomy (preferred bypass procedure)
  • Other bypass procedures may be used if needed.
  • Do not resect the annular pancreatic tissue, as this increases the risk of pancreatic injury and complications.

Complications

  • Duodenal obstruction (most common)
  • Acute pancreatitis
  • Chronic pancreatitis
  • Biliary obstruction (may cause jaundice)
  • Peptic ulcer disease
  • The main complications result from compression of the duodenum and nearby biliary/pancreatic ducts.

Prognosis

  • Excellent prognosis in asymptomatic patients; no treatment is usually needed.
  • Good prognosis after surgical bypass (e.g., duodenoduodenostomy), with relief of duodenal obstruction in most patients.
  • Prognosis depends on the severity of obstruction and the presence of complications (e.g., pancreatitis or biliary obstruction).
  • Early diagnosis and treatment generally lead to favorable outcomes.

Key Points / Clinical Pearls

  • Rare congenital anomaly with pancreatic tissue surrounding the second part of the duodenum.
  • Caused by abnormal migration of the ventral pancreatic bud.
  • Presents with duodenal obstruction or may be asymptomatic.
  • CT or MRI confirms the diagnosis.
  • Asymptomatic: Observation only.
  • Symptomatic: Duodenoduodenostomy (bypass surgery) is the treatment of choice.
  • Main complications: Duodenal obstruction, pancreatitis, and biliary obstruction.
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