In South Korea, the annual numbers of therapeutic ERCPs have consistently increased, and the extraction of CBD stones is the most common indication.8ref9-10 Along with the increased volume of ERCPs, the cases of difficult CBD stones would have increased because approximately 10% to 15% of patients with biliary stones are known to have challenging situations to extract the biliary stones.2,11 Thus, the competence of dedicated techniques for ERCPs is an essential part as an advanced endoscopist. With the advances of various technical skills and instruments for therapeutic procedures, such as POC with laser lithotripsy, extracorporeal shock wave lithotripsy, and balloon enteroscope, it is vital to keep abreast of the novel approaches. Accordingly, it is important to know the current practice patterns regarding the management of difficult CBD stones as an initial step to guide future taskforce recommendations and performance metrics related to health-care quality improvement.

Difficult biliary stones are regarded as any clinical situations that biliary stones cannot be successfully extracted only with standard techniques. The difficulties are related to various factors: (1) stone-related factors, such as their large diameter, number, slippery shape, or location (intrahepatic or cystic duct) and (2) anatomy-related factors, such as periampullary diverticulum, acute angulation or stricture in the bile duct, and surgically altered anatomy of Roux-en-Y anastomosis or Billroth-II anastomosis.

For the extraction of CBD stones, the adequate opening of ampullary orifice is prerequisite and usually obtained by conventional EST. However, in case of difficult CBD stones, a larger opening of the orifice is necessary to facilitate the removal of large stones. Furthermore, novel techniques can be implemented with new instruments considering the 0

stone characteristics or bile duct configuration; otherwise, other rescue procedures such as interventional radiology or POC could be applied as an alternative of ERCP, which is also an important capability for the management of the difficult stones. Therefore, the best patient outcomes for biliary stone management can be ensured by the complex and multifaceted approaches.

Regarding the size criteria for large CBD stones, this survey revealed that 40% of respondents agreed with the 15 mm criteria, which is the size mostly cited in many literatures including 2019 ESGE guideline for CBD stones;12 on the other hand, about 35% answered that the stones with more than 20 or 30 mm are considered large CBD stones. Interestingly, about 75% answered that the most preferred technique for gaining the adequate opening of ampullary orifice was “EPLBD after EST” which is firstly recommended technique by the ESGE 2019 guideline.12 Regarding the details of EPLBD, a 13 to 15 mm-sized balloon and 1-minute duration were the most preferred. Particularly, regarding the rescue techniques for difficult biliary cannulation in patients with periampullary diverticulum, a considerable portion (63.9%) of the respondents preferred DGW technique although the DGW technique was reported to have a higher rate of post-ERCP pancreatitis.13 About a quarter (26.7%) of the respondents preferred wire-guided cannulation over a pancreatic stent after the stent placement on the pancreatic duct, which seems to be more reasonable because prophylactic pancreatic stenting especially after the DGW has been widely accepted to reduce the risk of post-ERCP pancreatitis.14

In case of incomplete clearance of bile duct stones, temporary biliary stent placement (78%) was considered as the most preferred rescue measure in considering follow-up ERCPs; however, cholangioscopy-assisted lithotripsy was considered in only about 10% of participants despite of the high efficacy of POCs for the difficult biliary stones.15 This low preference can be attributed to the inadequate reimbursement for POCs, thereby causing the high medical cost of performing this procedure especially in South Korea.16 In addition, extracorporeal shock wave lithotripsy was rarely performed, and it may be attributed to the non-coverage for the purpose of biliary stone fragmentation by health-care insurance system in South Korea.

ERCPs in patients with surgically altered anatomy, such as Billroth-II anastomosis or Roux-en-Y reconstruction is well known for its technical challenges because of anatomical variabilities with long and tortuous afferent limb to reach the papilla. Even if successfully intubated, the inverted appearance of the papilla in endoscopic view is another hurdle to cannulate the bile duct, thereby leading to the difficulties for the management of biliary stones.17 A survey study from Japan society showed that balloon-assisted enteroscope was most frequently tried techniques both for Billroth and Roux-en-Y reconstruction.18 However, our study showed different results from the survey from Japan. For dealing with surgically altered anatomy, cap-fitted forward endoscope (77%) for Billroth-II anastomosis and percutaneous transhepatic cholangioscopy (48.8%) for Roux-en-Y anastomosis were the preferred techniques, respectively. Moreover, balloon-assisted enteroscopy was considered as low as about 1% for the first approach to deal with the surgically altered anatomy in South Korea.

This study is the first national survey to investigate the patterns of preferred endoscopic procedure types and techniques for managing difficult CBD stones in South Korea; however, there is a possibility of selection bias because the survey was only for the members of KPBA. Thereby, this survey showed about two-thirds of the respondents are highly experienced endoscopists who work at tertiary hospitals or academic hospitals with at least more than 5-year experience and more than 300 annual cases of ERCP. However, in South Korea, about 65% of the ERCP procedures are performed in at least higher setting of academic hospitals, which is demonstrated by a nationwide database study with Health Insurance Review & Assessment Service by KPBA in 2019,9 and the workplace setting of ERCPs is quite similar to our study results; thereby, the possibility of selection bias may not significant to hinder the representativeness of South Korea.

In conclusion, this study shows that most gastroenterologists who perform ERCP in South Korea have unifying trends for the management of difficult situations of bile duct clearance although the capability of dedicated armaments for POCs varies between each participant’s hospital. The current practice patterns would be used as basic data for clinical quality improvement regarding the management of difficult CBD stones.