The role of biliary obstruction in the pathogenesis of acute pancreatitis in the opossum.

Pancreatitis was induced in the opossum by occluding the common bile duct above or below the entrance of the pancreatic duct. The common channel theory was tested by evaluating the effect of preligation of the pancreatic duct to prevent the reflux of bile after ligation of the distal common duct. The severity of the disease was determined by histologic grading of the degree of pancreatic tissue necrosis. Serum amylase, lipase, and calcium were determined. Concomitant obstruction of the biliary and pancreatic ducts produced severe necrotizing pancreatitis whether or not bile reflux was present. Pancreatic ductal obstruction alone was associated with acinar atrophy and mild interstitial pancreatitis. Biliary obstruction alone above the entrance of the pancreatic duct resulted in marked hyperemia of the gland but without histologic evidence of pancreatic inflammation. A positive bacterial culture of the pancreas was obtained in only four of 36 opossums in a distribution to suggest random contamination. There was an inverse correlation between calcium levels and the degree of tissue necrosis. This study demonstrates that biliary obstruction rather than bile reflux into the pancreas is a requisite for the pathogenesis of severe biliary pancreatitis in this model.