ERCP is the acronym of Endoscopic Retrograde Cholangio-Pancreatography, which is an endoscopic technique of injecting contrast agent through the duodenal papilla to retrograde the pancreaticobiliary duct. In 1968, Mccune, an American scholar, first reported ERCP; in China, it started in 1973, and after years of clinical practice, it has become an important tool for clinical diagnosis and treatment of biliary and pancreatic diseases. EST is the acronym of endoscopic sphincterotomy, which means the endoscopic sphincterotomy of the large duodenal papilla through the catheter electrodissection. Classen in 1973 and 1974, respectively, and was performed in China in the early 1980s. The following is a brief description of the procedure of ERCP and EST with the example of endoscopic common bile duct lithotripsy: The endoscopic common bile duct lithotripsy is performed with an electronic endoscope called duodenoscope, which can be easily passed from the mouth through the esophagus and stomach into the descending duodenum, where there is an elevated part of the wall called the duodenal papilla, which is the exit point of the common bile duct. A special plastic catheter is introduced from the working channel of the endoscope and inserted through the duodenal papilla into the common bile duct. Contrast is then injected into the common bile duct through the catheter, and the location, number, and size of stones in the bile duct can be very clearly shown under X-ray fluoroscopy. There is a group of smooth muscles called the sphincter of Oddi in the duodenal papilla, which is used to control the secretion of bile in the bile duct, but the sphincter makes the opening of the common bile duct very small, and it must be cut open before removing the stone. The original inserted in the common bile duct of the special plastic catheter has a thin hair-like metal wire, through the handle can be tightened metal wire and make the front end of the plastic catheter outside the metal wire is bowstring-shaped, through the high-frequency current, the tightened metal wire will become an electric knife. The electric cutter is placed on the appropriate position of the duodenal papillary sphincter, and the duodenal papilla is slowly cut open, revealing a large opening at the end of the common bile duct. Since the high-frequency current coagulates the tissues it touches, the incision does not usually cause bleeding. At this point, the catheter is removed and replaced with a lithotripsy basket or balloon, which is inserted into the common bile duct, and the stone can be removed smoothly. If the stones are too large, a lithotripter can be used to mechanically crush the stones in the common bile duct before they are retrieved. Generally, the stones are not removed directly from the common bile duct, but are placed in the duodenum and allowed to pass naturally through the anus via the intestine.