Reply to Saritas and Ustundag

We thank Drs. Saritas and Ustundag for their interest and valuable comments [1] on our recent article comparing the yield of endoscopic ultrasound-guided choledochoduodenostomy (EUS-CDS) and endoscopic transpapillary stenting (ETS) in patients with malignant distal biliary obstruction [2].

As pointed out, the learning curve effect for EUS-CDS is an important issue. The specific expertise of each endoscopist for EUS-CDS and ETS was not shown in our study, and this lack of information was regarded as a limitation of the study [2]. Success in the EUS-CDS technique depends mainly on the expertise and skills of the operator (endoscopist). Another important component of technical success is the expertise of assistants for guidewire manipulation, fixation of the endoscope, and selection of devices. Despite lack of evidence, we currently suggest that 20 cases of EUS-CDS are sufficient for training and experience.

Some of the core technical training skills for EUS-CDS are: (i) visualizing the extrahepatic bile duct in the long axis from the duodenal bulb (operator), (ii) adjusting the direction of puncture toward the hepatic hilum (operator), (iii) fixing and keeping the endoscope in the duodenal bulb during visualization of the extrahepatic bile duct (second assistant), (iv) manipulation of the guidewire (0.025- or 0.035-inch hard type) and keeping it in the intrahepatic bile duct (first assistant), (v) use of a 6-Fr diathermic dilator (Cysto-Gastro-Set; Endo-Flex, GmbH, Voerde, Germany) for fistula creation between the duodenal bulb and the bile duct, and (vi) placement of a covered self-expandable metallic stent to prevent and minimize the possibility of bile leak and bleeding from the puncture site. A 6-Fr diathermic dilator is recommended because both the 8.5-Fr Cysto-Gastro-Set and the 10-Fr cystotome (Cook Medical, Bloomington, Indiana, USA) have larger diameters, resulting in a lower electric current density and a reduced diathermic effect, which are not sufficient for efficient fistula creation in terms of fistula size and procedure time.

As noted, various complications related to EUS-CDS have also been reported, such as bile leak [3] [4], stent dislocation [4] [5] [6], bleeding [3] [4], and perforation [3] [4]. However, procedure-related acute pancreatitis was not seen in our study [2]. At present, we should always be aware that there is no endoscopic retrograde cholangiopancreatography (ERCP) technique that can prevent post-ERCP pancreatitis completely [7] [8].

Regarding cost analysis, both ERCP and EUS-CDS are covered by insurance in Japan. The medical fee for EUS-CDS, excluding material cost, is JP ¥ 213 200 (about US $ 1887) and that for ETS is JP ¥ 115 400 (about US $ 1021). Therefore, at present, the cost of EUS-CDS is higher than that of ETS in Japan. However, the actual medical costs of EUS-CDS and ETS with regard to the management of complications were not analyzed [2]. In the near future, safety, feasibility, effectiveness, and all costs of EUS-CDS and ETS should be compared in a multicenter, randomized, controlled trial with a well-defined patient population and the expertise of multiple endoscopists.

Finally, in addition to the expertise of endoscopists, there is an urgent need for the development of dedicated devices (including stents) for safe, feasible, and effective EUS-CDS.

• References

• 1 Saritas U, Ustundag Y. Endoscopic ultrasound-guided choledochoduodenostomy vs. endoscopic transpapillary stenting. Endoscopy 2016; 48: 688
• 2 Kawakubo K, Kawakami H, Kuwatani M et al. Endoscopic ultrasound-guided choledochoduodenostomy vs. transpapillary stenting for distal biliary obstruction. Endoscopy 2016; 48: 164-169
• 3 Kawakubo K, Isayama H, Kato H et al. Multicenter retrospective study of endoscopic ultrasound-guided biliary drainage for malignant biliary obstruction in Japan. J Hepatobiliary Pancreat Sci 2014; 21: 328-343
• 4 Dhir V, Itoi T, Khashab MA et al. Multicenter comparative evaluation of endoscopic placement of expandable metal stents for malignant distal common bile duct obstruction by ERCP or EUS-guided approach. Gastrointest Endosc 2015; 81: 913-923
• 5 Kawakami H, Kuwatani M, Kawakubo K et al. Endoscopic salvage technique for spontaneous dislocation and tumor ingrowth of a partially covered, self-expandable metallic stent after endoscopic ultrasound-guided choledochoduodenostomy. Endoscopy 2014; 46: E58-E59
• 6 Kawakami H, Kuwatani M, Kawakubo K et al. Candy-like sign during endoscopic ultrasound-guided choledochoduodenostomy as an indication of the long distance between the bile duct and duodenal wall. Endoscopy 2014; 46: E406-E407
• 7 Kawakami H, Isayama H, Maguchi H et al. Is wire-guided selective bile duct cannulation effective for prevention of post-ERCP pancreatitis by all endoscopists?. Endoscopy 2014; 46: 163
• 8 Kawakami H, Kubota Y, Kawahata S et al. Transpapillary selective bile duct cannulation technique: a review of Japanese randomized controlled trials since 2010 and an overview of clinical results in precut sphincterotomy since 2004. Dig Endosc . In press 2016. DOI: 10.1111/den.12621.