[Real time echographic study of the normal Wirsung duct. Comparison with retrograde catheterization]

An ultrasonogram (US) of the pancreatic duct was performed in 59 patients prior to a retrograde pancreatography (ERCP). In 41 patients with normal ERCP, the pancreatic duct in the body of the pancreas was found to be on US less than 2 mm. The diameter measured on ERCP on the same portion of the pancreas was found to be 2,5 larger. On 18 abnormal ERCP, 3 patients had normal US defined by a pancreatic duct less than 2 mm in internal diameter and a normal pancreatic parenchyma. These 3 patients had mild ductal abnormalities of chronic pancreatitis on ERCP, undetectable by US. These 3 false negative cases give to a normal pancreatic US a negative predictive value of 93%. The injection of 5 normal autopsy pancreas, combined with US of the pancreatic duct, showed that neither the radiological magnification nor the pressure of injection accounted for the discrepancy between US and ERCP in the measurement of the pancreatic duct diameter. It is thought to be due to an underestimation of the internal diameter of the duct which may be related to an apparent thickening of its highly echogenic walls.