Pancreatic Divisum Types
Pancreatic divisum is classified into two main anatomical types: "classic" (complete) pancreatic divisum, where the dorsal and ventral pancreatic ductal systems fail to fuse entirely, and "incomplete" pancreatic divisum, where only partial fusion occurs between these embryological duct systems. 1
Classic (Complete) Pancreatic Divisum
Classic pancreatic divisum results from complete failure of fusion between the dorsal and ventral pancreatic ducts during the second month of embryogenesis. 2, 1
In this variant, the dorsal duct becomes the dominant main pancreatic duct and drains the majority of pancreatic exocrine secretions through the minor papilla, while the ventral duct (duct of Wirsung) remains separate and drains only a small posterior portion of the pancreatic head through the major papilla. 2, 3
The radiological hallmark is a short (1-6 cm) and thin (approximately 2 mm diameter) ventral pancreatic duct that branches into regular arborization and drains only the posterior head of the pancreas, with complete absence of communication between the dorsal and ventral systems. 3
MRCP demonstrates non-communicating dorsal and ventral ducts with independent drainage sites, a dominant dorsal pancreatic duct, and sometimes a small cystic dilatation of the dorsal duct at the minor papilla (santorinicele). 4
Incomplete Pancreatic Divisum
Incomplete pancreatic divisum occurs when the ventral and dorsal pancreatic buds only partially fuse during embryological development. 1
This variant represents a spectrum where some degree of communication exists between the dorsal and ventral ductal systems, but the connection remains inadequate for normal pancreatic drainage. 1
The dorsal duct still predominates as the main drainage pathway through the minor papilla, but unlike classic divisum, there is partial anatomical connection with the ventral system. 1
Clinical Significance of Classification
Both types occur in approximately 6-10% of the general population, making pancreatic divisum the most common congenital pancreatic anomaly. 5, 6, 7, 2, 3
The vast majority of patients with either type remain asymptomatic throughout their lives, though a subset may develop impaired drainage of pancreatic secretions through the dorsal-dominant system, potentially resulting in increased intraductal pressures and recurrent acute pancreatitis. 5, 6
The distinction between true pancreatic divisum and "false" pancreatic divisum (which can be simulated by previous pancreatic trauma, partial pancreatectomy, pancreatitis with irreversible ductal damage, pseudocyst, or pancreatic carcinoma) is clinically important because of different management implications. 3
Diagnostic Considerations
ERCP remains the gold standard for definitively diagnosing and classifying pancreatic divisum types, though MRCP with secretin enhancement is increasingly used as a non-invasive alternative that can greatly improve ductal visualization. 2, 4, 8
EUS is the preferred initial modality for evaluation of unexplained acute and recurrent pancreatitis, with MRI/MRCP serving as complementary tests particularly helpful for identifying pancreatic ductal anatomical variants. 5, 6, 7