LAUSR

The standard procedure for removing bile duct stones is endoscopic removal using endoscopic retrograde cholangiopancreatography (ERCP). However, removing common bile duct and/or intrahepatic stones from a patient with a surgically altered anatomy can be challenging. Recently, a balloon enteroscope with a wide channel, which can be used with a variety of devices, has become available. Stone removal using balloon enteroscopy-assisted ERCP (BEAERCP) has been reported to be safe and have a relatively high success rate. However, endoscope insertion and biliary cannulation may be unsuccessful, even when performed by experts, due to postoperative adhesions and long afferent limbs. In such situations, percutaneous transhepatic biliary drainage (PTBD) has been performed as a salvage technique after a failed BEA-ERCP procedure; however, a decrease in the patient’s quality of life remains an issue with this technique. Endoscopic ultrasound-guided biliary drainage (EUS-BD) has emerged as an alternative method for salvaging an unsuccessful ERCP procedure, especially in the case of a malignant biliary stricture. Furthermore, in recent years, an EUS-guided antegrade intervention (EUS-AI), which is an antegrade treatment that uses a fistula that is created by EUS-BD, has attracted attention. Compared with BEAERCP, PTBD, or surgery, EUS-AI has the advantage of a straightforward approach to the bile duct, a short procedure time, and the avoidance of several issues associated with an external drainage catheter. In fact, a previous study on drainage techniques for patients with a surgically altered anatomy showed that EUS-BD had a higher success rate and shorter procedure time than BEA-ERCP. However, the adverse event rate was significantly higher for EUS-BD (20% vs. 4%, respectively; P = 0.01), and the available devices were limited compared with BEA-ERCP. Therefore, BEA-ERCP, which is less invasive and safer, should be considered the first-line treatment for benign biliary diseases such as bile duct stones, and EUS-AI should be selected as an alternative treatment. Endoscopic ultrasound-guided antegrade stone removal is a type of EUS-AI, and it has been increasingly reported as a salvage technique that can be used after an unsuccessful stone removal using BEA-ERCP. With EUS-guided antegrade stone removal, the intrahepatic duct is punctured using a fine needle aspiration needle, and a guidewire is advanced through the ampulla into the duodenum. Subsequently, the ampulla is dilated using a dilatation balloon catheter, and the bile duct stones are pushed out across the ampulla in an antegrade fashion with an extraction balloon catheter. Following the complete removal of the stones, a temporary nasobiliary drainage tube or plastic stent is often placed into the bilioenteric fistula to prevent bile leakage. The authors of a multicenter retrospective study of EUSguided antegrade stone removal of bile duct stones for patients with a surgically altered anatomy reported a success rate of 72% and an adverse event rate of 17%. Although these results suggest that EUS-guided antegrade stone removal is an effective treatment for bile duct stones, there are some limitations. In cases where the bile duct is not completely obstructed, the EUS approachmay be challenging because of insufficient dilatation of the intrahepatic bile duct. Usually, a 19G needle combined with a 0.025-inch guidewire is used; however, in such cases a 22G needle combined with a 0.018-inch guidewire is preferred. Recently, a novel 0.018inch guidewire with improved stiffness was developed. Using a 22G needle combined with this novel 0.018-inch guidewire appears to be a safer and more feasible approach. Ampullary intervention is limited to papillary balloon dilation. Therefore, if the stones are larger than the size of the dilation balloon, biliary lithotripsy is required. However, this may prolong the procedure time and increase the risk of bile leakage. Furthermore, the limited availability of devices makes stone removal technically difficult. A two-step approach has been devised as a treatment option to resolve these limitations. In the first session, EUSguided hepaticoenterostomy is performed to create a fistula between the enteric canal and left intrahepatic bile duct. In the second session, antegrade stone removal is performed after the fistula has matured. Creation of a mature fistula reduces the risk of bile leakage. A mechanical lithotripter and peroral cholangioscope can be inserted easily through