Risk factors for developing PEP include technical matters related to the ERCP procedure and patient-specific ones. The technical factors include manipulation of and injection of contrast into the pancreatic duct, cannulation attempts lasting more than five minutes, and biliary balloon sphincter dilation; among patient-related factors are female gender, younger age, and Sphincter of Oddi dysfunction. A systematic review of clinical trials concluded that a previous history of PEP or pancreatitis significantly increases the risk for PEP to 17.8% and to 5.5% respectively.