Prior knowledge of the anatomy and physiology associated with pancreatobiliary diseases, medications for sedative endoscopy, proper antibiotic usage, informed consent, gastric endoscopy skill, and ERCP indications and contraindications.

Basic skills required for beginners, procedure types by difficulty level, and knowledge of radiation exposure.

The ability to prevent and manage procedure-related complications and report the results properly after the procedure.

To perform the procedure, the duodenoscope should be inserted safely into the second portion of the duodenum. Therefore, it is important that the operator understands the duodenal architecture and how to insert the scope into the esophagus, stomach, and duodenum. Because the duodenoscope is a side view scope and the tip is somewhat stiff, trainees may experience insertion difficulty. When the scope is inserted into the esophagus, the vocal cords are not located at the front of the visual field rather obliquely upward of the visual field. The scope should then be inserted into the vocal cords.

When the pyloric ring is passed, the position of the pylorus is checked and placed at the 6 o’clock position without its placement in the front of the field of view. The endoscopist then gently pushes the scope to insert it into the descending portion. The endoscope is then shortened using the pulling method to naturally allow the distal end of the endoscope to approach the descending portion of the duodenum. Upon shortening, the endoscope appears as an L shape on the contrast. If there is difficulty approaching the papilla through this shortening method, due to duodenal axis deformity or duodenal diverticulum, the endoscope can be pushed to maintain the long axis and approach the papilla.

Although insertion of the duodenoscope is the most basic component of the ERCP procedure, duodenal perforation may occur during the insertion and pulling procedure.

After the endoscope insertion into the duodenum, the operator should be trained to enable selective cannulation of the biliary or pancreatic duct through the papilla. Successful catheter insertion into the biliary or pancreatic duct through the papilla is the most basic step in further treatment, so the operator must be aware of the selective cannulation method. With a normal papilla, the 11 o’clock direction of the endoscopic view shows the bile duct, while the 1 o’clock to 5 o’clock direction of the endoscopic view shows the pancreatic duct.

After training, the KPBA guidelines state that the ERCP trainee’s success rate should be >80% [4]. The ERCP trainees should also be trained in rescue methods such as fistulotomy using a needle knife or precut sphincterotomy if standard cannulation fails. Because these procedures are more likely to cause complications, they should be performed after sufficient guidance from a trained specialist. The rescue procedure should not be used primarily and not be used in more than 10%–15% of total ERCP procedures.

Sphincterotomy is also a most basic procedure of ERCP. Trainees should be familiar with adaptation of the papillotomy and its implementation. It is also necessary to understand complications such as hemorrhage or perforation after sphincterotomy. Sphincterotomy is usually performed using a pull-type spincterotome after guidewire insertion into the bile duct. However, it must be careful not to perform sphincterotomy too fast. Since the catheter is sometimes inserted into the pancreatic duct, pancreatic sphincterotomy including its indications and complications should be understood as well.

Balloon dilatation is mainly used to enlarge the papillary orifice for removal of large CBD stones. Because procedure-related complications such as pancreatitis, hemorrhage, and perforation may occur, it is advisable that the operator selects the proper target and gradually expands the duct during the procedure. It can also be used to expand the stenosis of the bile or pancreatic duct. The balloon diameter should not be larger than that of the proximal portion of the stenosis. ERCP trainees should be aware of the exact indications for this procedure and avoid stretching for long stenotic lesions because of insufficient study results.

The removal of CBD stones is a major indication for ERCP and one of the most commonly performed procedures. KPBA guidelines state that the CBD stone removal and bile duct drainage success rate should be ≥85% [4]. Balloons and baskets are mainly used to remove stones, while techniques such as mechanical lithotripsy, electrohydraulic lithotripsy, or laser lithotripsy may be necessary. Electrohydraulic or laser lithotripsy should be performed in a highly skilled and well-equipped situation. It is important that the operator be aware of the risk of stones trapped in the basket and be trained to perform mechanical lithotripsy.

ERCP trainees should be aware of the importance of proper drainage after contrast media is injected into the proximal portion of the occlusion and familiar with stenting indications and types. Current stent types include plastic and metal. Operators should be aware of stent types, lengths, diameters, and characteristics. Causes of bile duct obstruction include malignant obstruction, large CBD stones that are difficult to remove, benign strictures due to chronic pancreatitis, or bile duct injury after surgery. Bile duct obstruction caused by these conditions is a common indication for drainage, especially in the presence of jaundice or cholangitis due to bile duct obstruction. KPBA guidelines recommend a successful biliary stent insertion rate ≥80% [4]. In addition to therapeutic stent insertion, special circumstances such as pancreatic stent insertion for the prevention of post-procedure pancreatitis should be recognized.

Post-ERCP pancreatitis, the most common ERCP complication, is known to occur in 1%–7% of patients except for those with sphincter of Oddi dysfunction or pancreatic duct treatment [13]. The incidence of pancreatitis after ERCP varies by endoscopist experience and procedural difficulty. Risk factors of post-ERCP pancreatitis are divided into two categories: patient and technique. Patient-related factors include younger age, suspected sphincter of Oddi dysfunction, history of previous post-ERCP pancreatitis, and normal serum bilirubin. Women may be at increased risk, but it is difficult to determine the confounding effect of sphincter of Oddi dysfunction, a condition that occurs almost exclusively in women. Technique-related factors include papillary trauma by repetitive cannulation, acinarization of the pancreas by contras injection, and pancreatic sphincterotomy. To reduce the incidence of post-ERCP pancreatitis, guidewire or hybrid technique using minimal contrast in combination with wire probes, pancreatic duct stent in specific situations such as biliary sphincterotomy for sphincter of Oddi dysfunction, suspected sphincter of Oddi dysfunction with normal manometry, pancreatic sphincterotomy, precut sphincterotomy, balloon dilation of the biliary sphincter, and endoscopic ampullectomy can be used after pancreatic wire-assisted biliary cannulation, probably after difficult cannulation, and even after unselected ERCP in patients with “virgin papilla,” excluding those with pancreas divisum or cancer [14].

Perforation due to ERCP is known to occur in approximately 0.1%–0.6% of cases, and in patients with normal anatomical structure, a perforation rate of <1% is expected [13]. Perforation by a simple guidewire does not usually require surgery and can usually be managed conservatively (fasting, fluid, and antibiotics), and perforation of the biliary or pancreatic duct can be treated with a stent. In contrast, esophageal and gastric perforation require surgery. Both conservative management and surgery are considered in cases of small perforations of the posterior duodenal wall [15].

Bleeding during ERCP is common and does not represent an adverse outcome. As a result, post-ERCP bleeding is defined as immediate hemorrhage requiring endoscopy or another intervention, while delayed hemorrhage is defined as hemoglobin reduction or hemorrhage requiring transfusion within 10 days after the procedure. Post-ERCP hemorrhage is observed in approximately 1% of cases, but most cases are mild hemorrhage. Bleeding risk after major sphincterotomy is known to occur in up to 2% of cases [13]. Methods to prevent hemorrhage after sphincterotomy are balloon dilatations of sphincters, correction of any coagulopathies, withholding of anticoagulant medications for as many as 3 days afterward, and use of a meticulous endoscopic technique. For the treatment of significant hemorrhage, several endoscopic treatments such as injection of dilute epinephrine, balloon tamponade, and thermal therapy can be used. In cases of refractory bleeding, angiographic therapy is rarely used [14].