Pancreas divisum

Failure of the dorsal and ventral ducts to fuse during embryogenesis

• Leads to partial obstruction of the main pancreatic duct at the minor papilla, leading to chronic back pressure
• May cause relapsing acute or chronic pancreatitis

Epidemiology

• Most common variant of dominant dorsal duct anatomy
• As common as left-handedness - 10%

Pathophysiology

• Controversial as to whether it actually causes pancreatitis
  • Could outflow obstruction at minor papilla be responsible?
  • Could there be some other underlying genetic abnormalities? It's associated with a higher prevalence of genetic mutations that predispose to pancreatitis.
  • Patients referred for ERCP with pancreatitis have higher incidence of pancreas divisum than expected
  • Sphincterotomy or stenting minor papilla does reduce the rate of recurrent pancreatitis
    • If that fails and patients remain symptomatic, or chronic pancreatitis/local complications occur, consider surgery (sphincteroplasty, pancreaticoduodenectomy, duodenum-preserving pancreatic head resection)

Embryology

• Pancreas formed by fusion of ventral and dorsal buds
• 6th to 7th week: ventral bud rotates clockwise to fuse with the dorsal bud
• Usually, the ventral duct becomes dominant (duct of Wirsung) and duct of Santorini (dorsal duct) is minor.
• If fusion is incomplete, the dorsal duct drains the majority of the pancreas through its SMALLER orifice, and the ventral duct joins with the CBD to drain through the major papilla
• The minor papilla is usually just proximal to the major papilla
• Can be complete or incomplete fusion

Acquired pancreas divisum/pseudodivisum

• A/w chronic pancreatitis and malignancy
• Total occlusion of ventral duct, causing dorsal duct to assume responsibility for pancreatic exocrine outflow via the minor papilla
• If this diagnosis is questioned but no mass is seen on CT/MRI, EUS should be performed

Presentation

• Usually asymptomatic - only 5% of patients present with chronic abdo pain, recurrent pancreatitis or chronic pancreatitis
• Rarely develops into severe fibrosing chronic pancreatitis
• Most common presentation is patients with chronic pain intractable to medical management
• Uncommon for acute pancreatitis a/w pancreas divisum to lead to pancreatitis and peripancreatic necrosis - usually self-limiting

Diagnosis

• MRCP is best modality, and secretin-enhanced MRCP can improve visualisation of congenital pancreaticobiliary malformations
  • Indicated with frequent presentations for pancreatitis

Management

• Aims: improve drainage and resect damaged tissue

Indications for intervention

• Endoscopic sphincterotomy
  • Pancreatic-type pain in association with obstructive morphology (dilated pancreatic duct or santorinicoele)
  • Documented recurrent acute pancreatitis without another clear and reversible cause