Is it time to stop using percutaneous transhepatic biliary drainage?Referring to Paik WH et al. p. 544–548
30 May 2017 (online)
The role of endoscopic ultrasound (EUS) has evolved considerably in recent years. At inception, EUS was an exclusively diagnostic modality; however, the therapeutic potential of EUS continues to be realized, most notably in techniques for EUS-guided biliary drainage (EUS-BD).
In skilled hands, EUS-BD can be utilized for primary therapy in patients with an inaccessible papilla due to malignant obstruction or surgically altered luminal anatomy, or as secondary therapy in those with biliary obstruction and prior incomplete biliary drainage when conventional endoscopic methods fail (i. e. endoscopic retrograde cholangiopancreatography [ERCP]) . Historically, such patients underwent percutaneous transhepatic biliary drainage (PTBD), with or without subsequent internalization, depending on the clinical scenario and technical feasibility . The technique of internal conversion of PTBD using EUS-guided hepaticogastrostomy (EUS-HGS) was first proposed by Chopin-Laly et al.  in a patient with unresectable pancreatic cancer and a post-cholecystectomy bile duct transection. Following external PTBD, internalization of drainage was achieved electively via EUS-HGS and placement of a covered self-expandable metal stent (cSEMS), allowing for subsequent removal of the percutaneous drain. A similar technique was described recently for the EUS-guided conversion of percutaneous gallbladder drainage to internal biliary drainage utilizing a lumen-apposing metal stent (LAMS) in patients with cholecystitis who were deemed medically unfit for subsequent cholecystectomy .
In this issue of Endoscopy, Paik et al.  present retrospective outcome data on elective internal conversion of PTBD using EUS-HGS following failed internalization via the percutaneous route in patients with malignant distal biliary obstruction (≥ 2 cm distal to the hepatic hilum). This pilot study of 16 patients, which was conducted in two tertiary care academic medical centers in Korea and Japan, demonstrates high technical and clinical success (100 % and 81 %, respectively), with an acceptable rate of adverse events (13 %), utilizing EUS-HGS. Two adverse events (cholecystitis and proximal [intrahepatic] stent migration) and four episodes of stent occlusion occurred during the follow-up period, and were managed without the need for additional percutaneous drainage or surgical intervention. EUS-guided internalization allowed the removal of the PTBD catheter in a mean of 4.6 days. Overall, this study provides high-quality preliminary data to further expand the indications for EUS-BD to include internalization of external biliary drainage.
“While the results from Paik et al. are encouraging, and add to the growing list of indications for EUS-BD, cautious optimism should be exercised as additional studies are warranted.”
The presented study only included patients with unresectable distal biliary malignancies, generally a population with a paucity of therapeutic options and limited life expectancy. EUS-HGS internalization in this setting has clear technical advantages over percutaneous internalization, as adequate drainage can be obtained through left intrahepatic access, obviating the need for guidewire navigation across the strictured distal bile duct; in contrast, internalization via a percutaneous catheter cannot be achieved without traversing the stricture for access to the small bowel. In addition EUS-HGS involves stent placement through healthy tissue which may provide extended patency when compared to internal PTBD.
Future studies should aim at translating EUS-BD internalization techniques to additional populations, such as those with hilar malignancies or patients with benign biliary obstruction (i. e. post-transplant anastomotic strictures, other post-surgical strictures [hepaticojejunostomy, choledochoduodenostomy, cholecystectomy, hepatectomy]) who previously underwent PTBD. Patients with hilar malignancies involving one or both main hepatic ducts probably represent the most complex cohort for EUS-guided internalization, as the right and left hepatic ducts may need to be accessed separately (i. e. hepaticogastrostomy to a left intrahepatic duct and hepaticoduodenostomy to a right intrahepatic duct) . Techniques to access the right system following transmural puncture into the left system have also been described.
Available data on EUS-BD in patients with benign post-surgical strictures are limited. Miranda-Garcia et al.  recently described the utility of EUS-BD in seven patients using a two-step approach: EUS-HGS followed by antegrade stricture dilation with or without antegrade stent placement, if possible. Technical success (EUS-HGS + dilation + stent placement) was achieved in four patients; however, clinical success was achieved in 100 % of patients owing to biliary drainage via the hepaticogastrostomy when antegrade stenting failed. EUS-BD approaches in patients following liver transplantation have not been formally studied and remain limited to case reports  .
The decision to pursue EUS-BD in patients with benign post-surgical biliary obstruction is complex and is likely to require a multidisciplinary discussion with vested parties (i. e. surgeons, interventional radiologists, hepatologists, etc.) prior to commencing. However, this is a patient population who may require long periods of external (or external – internal) PTBD, or even percutaneous transjejunal catheters in selected circumstances . Further development of EUS-BD internalization strategies for patients with a benign indication for long-term biliary drainage would likely translate into improved quality of life.
While the results from Paik et al. are encouraging, and add to the growing list of indications for EUS-BD, cautious optimism should be exercised as additional studies are warranted. In current practice, EUS-BD remains technically demanding, even for the most experienced therapeutic endoscopists, thereby limiting widespread adoption of EUS-BD for internalization of percutaneous biliary drainage catheters. When compared with percutaneous biliary drainage, available data suggest superiority of EUS-BD in terms of technical success and adverse event profile when performed in experienced hands . Despite these findings, PTBD remains the accepted “standard of care” at most medical centers for the management of these complex clinical scenarios.
The current trajectory of EUS-BD suggests a bright future. However, deposing PTBD in the current management algorithm will require: 1) further refinement of current techniques; 2) continued expansion of procedural indications in order to provide enough case volume to develop/maintain competence; 3) improvement and commercialization of procedural accessories designed specifically for EUS-BD procedures; and 4) increased exposure and training, including implementation of high-fidelity models for therapeutic endoscopists wishing to take on these procedures  . The growing number of centers incorporating EUS-BD, and the improved outcomes reported in the latest vs. earlier reports are indirect evidence that some of these developments are taking place . Dedicated stents for EUS-BD show promise in either pilot trials of plastic stents  and LAMS , or even in randomized comparisons with standard SEMSs .
Nonetheless, even if the ideal requisites for EUS-BD become present, PTBD will still be required after failed ERCP in those patients without visible intrahepatic dilation and hilar obstruction. The question may therefore not be whether PTBD should no longer be used, but rather, whether it should be replaced by EUS-BD in patients where EUS-BD is feasible, or the two techniques combined electively in the difficult patient subset where EUS-BD is not technically possible and PTBD cannot be internalized. If the temporary clamping or injection techniques described by Paik et al. to internalize PTBD prove easily reproducible, it can be claimed that there is no reason why this should not be tried in order to prevent patients with malignant biliary obstruction from being left with the suboptimal palliation offered by permanent external biliary drainage.