Gallstones are stones formed in the gallbladder and bile ducts. In general, gallstones may cause pancreatitis, especially some smaller stones, such as those around 1 cm in diameter. Because stones of about 1 cm can be easily expelled, they can easily become lodged in the opening of the pancreatic duct at the lower end of the common bile duct, blocking the pancreatic duct and leading to pancreatitis. Gallstones can be divided into gallbladder stones, intrahepatic bile duct stones, and extrahepatic bile duct stones. Gallbladder stones may detach from the cystic duct and enter the common bile duct, thus causing obstruction of the lower end of the common bile duct, leading to pancreatic duct obstruction and consequently pancreatitis. Extrahepatic bile duct stones, which themselves are located inside the common bile duct, can cause obstruction of the opening of the pancreatic duct if they are dislodged to the lowest position, leading to symptoms of pancreatitis. In some cases, intrahepatic bile duct stones may be dislodged directly from the intrahepatic bile duct and enter the common hepatic duct and common bile duct, leading to obstruction of the pancreatic duct opening and pancreatitis. If gallstones cause pancreatitis, further surgery should be considered. After pancreatitis has occurred, there is a high probability that the stones will be dislodged again and lead to recurrence of pancreatitis. In addition, repeated episodes of pancreatitis may worsen the condition and even lead to severe pancreatitis, which can be life-threatening.