Reply to Rimbaș et al.

We greatly appreciate the comments of Rimbaș et al. in their letter [1] regarding our recent study that compared the use of endoscopic ultrasound-guided choledochoduodenostomy (EUS-CDS) and endoscopic transpapillary stenting (ETS) in the treatment of malignant distal biliary obstruction [2]. We would like to reply to some of their comments.

The usefulness of EUS-CDS in the treatment of patients with malignant distal biliary obstruction has been reported [3]. The advantage of EUS-CDS over ETS was shown in our study [2]. However, 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]. As Rimbaș et al. point out, the usefulness of EUS-CDS should be confirmed by a multicenter randomized controlled study (RCT) with a well-defined patient population and expert endoscopists.

The self-expandable metallic stents (SEMSs) used in our study were wire-braided, partially covered, tubular SEMSs [2]. Stent dislocation is less likely to occur when using partially covered, rather than fully covered, tubular SEMSs. The local progression of a tumor may also cause stent dislocation [5]; however, this can also occur in ETS. The flared ends of the partially covered SEMSs can cause biliary injuries and perforations; however, no complications were reported among individuals from the EUS-CDS group in our study [2]. One of the core technical tips for preventing biliary injuries involves the following deployment process: (i) starting SEMS deployment in the intrahepatic bile duct, (ii) pulling the SEMS back to just below the hepatic hilum, and (iii) completing SEMS deployment, keeping the proximal end of the stent in this position. A biflanged, lumen-apposing, fully covered SEMS (LA-SEMS) incorporated within a delivery system [7] that contains an electrocautery device mounted on the tip is surely an interesting device [8]. However, whether a tubular SEMS or biflanged LA-SEMS is best for EUS-CDS remains to be elucidated. We believe that a 6-Fr diathermic dilator (Cysto-Gastro-Set; Endo-Flex, GmbH, Voerde, Germany) is essential for EUS-CDS using tubular SEMS in order to create the fistula between the duodenum and the bile duct. However, the safety and feasibility of this device should be confirmed by a multicenter RCT.

Unfortunately, biflanged LA-SEMSs are not yet available in Japan. However, we speculate that biflanged LA-SEMSs are more likely to cause food impaction. No evidence of food impaction was found in our study when EUS-CDS was performed using tubular SEMSs. Immediately after deployment, the distal end of the tubular SEMS tends to face the oral side. However, it turns to face the opposite direction within a few days, possibly as a result of intestinal peristalsis; this position can be confirmed by radiography, without further intervention. Caution should be exercised in cases of duodenal invasion, as the direction of the tubular SEMS may not be fixed in these instances. However, despite being urgently needed, no dedicated devices or stents have been developed for EUS-CDS.

The education and training of the new generation of endoscopists are two important issues. Pancreaticobiliary endoscopists should be familiar with both endoscopic retrograde cholangiopancreatography (ERCP) and EUS. EUS-CDS may be used when ETS fails and vice versa; percutaneous transhepatic biliary drainage may be necessary in some cases. Finally, no acute pancreatitis was seen in our study [2]. To date, no technique has been shown to prevent the post-ERCP pancreatitis that results from ETS [9] [10]. As a result, the safety and feasibility of EUS-CDS should be confirmed by a multicenter RCT.

• References

• 1 Rimbaș M, Kunda R, Larghi A. Endoscopic ultrasound-guided choledochoduodenostomy as a primary treatment for malignant distal biliary obstruction: is it time for a randomized controlled study?. Endoscopy 2016; 48: 686
• 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 Itoi T, Binmoeller KF. EUS-guided choledochoduodenostomy by using a biflanged lumen-apposing metal stent. Gastrointest Endosc 2014; 79: 715
• 8 Rinninella E, Kunda R, Dollhopf M et al. EUS-guided drainage of pancreatic fluid collections using a novel lumen-apposing metal stent on an electrocautery-enhanced delivery system: a large retrospective study (with video). Gastrointest Endosc 2015; 82: 1039-1046
• 9 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
• 10 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.