Serum amylase, pancreatic stents, and pancreatitis after sphincter of Oddi manometry

Background: Serum amylase levels 2 hours after ERCP predict postprocedure pancreatitis. The value of serum amylase measurements after sphincter of Oddi manometry (SOM) and the effect of pancreatic-duct stent placement on serum amylase are unknown. Methods: Records were reviewed for 88 SOM patients who had serum amylase measured 2 hours after the procedure. Post-SOM pancreatitis was defined as pain with a >3-fold elevation of serum amylase on the morning after SOM. "Possible pancreatitis" was defined as pain with a <3-fold elevation of serum amylase on the morning after SOM. Results: Post-SOM pancreatitis and possible pancreatitis each occurred in 13% of the study cohort. Post-SOM pancreatitis was associated with the absence of a pancreatic stent and occurred in 0% of patients without a stent who had normal 2-hour serum amylase vs. 67% with elevated 2-hour serum amylase (p < 0.01). Among patients who received a stent, pancreatitis occurred in 6%, regardless of whether the 2-hour serum amylase was elevated. Possible pancreatitis occurred mainly in patients who received stents, and it also was associated with elevation of the 2-hour serum amylase. Conclusions: Elevation of the serum amylase level 2 hours after SOM predicts post-SOM pancreatitis but only in patients who do not receive a pancreatic stent. Among patients who received a stent, elevated 2-hour serum amylase levels predict subsequent findings that may be caused by attenuated pancreatitis.