Pancreatic response to percutaneous biliary drainage: a prospective study. To evaluate the effects of percutaneous biliary drainage (PBD) on the pancreas, serum amylase levels were measured for 7 consecutive days after PBD and compared with baseline values in 50 patients who underwent a total of 53 PBD procedures. Of the 45 patients with normal baseline serum amylase levels, 12 patients (24%) developed postprocedural hyperamylasemia without clinical symptoms and five patients (10%) developed postprocedural hyperamylasemia with clinical signs of pancreatitis. Five patients who presented with elevated baseline serum amylase levels demonstrated decreases into the normal range after placement of stents without initiation of bowel rest or liquid diet. The level of biliary obstruction proved insignificant, as did the nature of the obstructing disease, in determining which patients would experience hyperamylasemia or pancreatitis after PBD. It is concluded that the frequency of pancreatic insult from PBD may be more common than previously reported and that patient susceptibility is not dependent on the level of biliary obstruction or the nature of the disease. 