Endoscopic ultrasound-guided ductal access and drainage – thus far and much further

Obstructive pancreaticobiliary diseases are morbid conditions associated with significant disease burden. Historically surgical drainage, percutaneous transhepatic biliary drainage (PTBD), and endoscopic retrograde cholangiopancreatography (ERCP) have been the procedures of choice for ductal drainage and access. Recently, endoscopic ultrasound-guided ductal access and drainage (EUS-DAD) has revolutionized pancreaticobiliary therapy. Successful biliary drainage of malignant biliary obstruction has now become the standard of care because neoadjuvant therapy for pancreaticobiliary malignancies prior to surgery has shown improved survival compared with primary surgical resection.

“EUS-DAD is a unique procedure needing a high level of EUS competence and expertise and is an alternative back-up procedure in centers with high ERCP volumes.”

Pancreatic ductal therapy has been performed mainly by ERCP. Previously, the sole alternative to failed ERCP was surgery. Recent advances in EUS-DAD have now made this a preferred alternative to failed ERCP, where available. However, EUS-DAD for the pancreas is not widely available and has not been well studied, with very few published case series of small size and limited success [1].

Even in high-volume ERCP referral centers, there is a finite limit to the success of ERCP, with the ERCP failure rate ranging from 2 % to 10 %. The traditional alternative to failed ERCP has been PTBD. EUS-guided biliary drainage (EUS-BD) now offers a minimally invasive endoscopic alternative with many advantages over PTBD. The first use of EUS-DAD was reported by Giovannini et al. in 2001 [2]. Since then, a few small randomized controlled trials have been conducted comparing EUS-BD to ERCP [3] [4] [5], EUS-BD to PTBD [6], and the different techniques for EUS-BD [7]. There have also been many retrospective studies and systematic reviews/metanalyses [8]. Taken together, these studies have established high rates of technical and clinical success, with lower or equivalent adverse event rates.

The article by Garcia-Alonso et al. represents a real-world practical analysis of their experience in using the EUS-guided techniques and how these techniques complement traditional ERCP [9]. This single-center study followed a large number of ERCPs performed in a tertiary referral academic institution. Although the data were collected prospectively, the analysis was done retrospectively. The most remarkable finding of this large study is that only 0.1 % of the cases (3/2205) required PTBD. EUS-DAD for the bile duct was required in 7.7 % of cases (170/2205) and for the pancreatic duct in 10 % of cases (10/104). The highly favorable results of the study show that ERCP enhanced by EUS-DAD brings complex pancreaticobiliary duct disease within the reach of endoscopic therapy, thereby negating the need for percutaneous drainage in the management of the vast majority of patients [9]. There are some limitations to the study, namely its retrospective nature, the heterogeneity of practice patterns and diagnoses, and the lack of adverse event information and other relevant intraprocedural data.

EUS-DAD is a unique procedure needing a high level of EUS competence and expertise and is an alternative back-up procedure in centers with high ERCP volumes. Therefore, it follows that when high quality ERCP is available, by definition, the number of cases requiring EUS-DAD will be few. As a result, gaining experience and developing protocols can be challenging.

The next major issue is the availability of specialized interventional EUS-DAD tools. Most EUS-DAD procedures are currently performed with tools designed for other endoscopic procedures by experienced pancreaticobiliary endoscopists who have skillfully adapted these to EUS therapeutics. There are a few specifically designed tools now available for EUS-DAD, such as a steerable EUS-guided fine-needle aspiration (EUS-FNA) needle for wire guidance, specialized stents for hepaticogastrostomy, and lumen-apposing metal stents with cautery tip for choledochoduodenostomy. Unfortunately, the availability of these tools across the world is not uniform. The development of specialized tools is an important aspect of furthering new and innovative procedures like EUS-DAD. Multicenter, academic, and industry collaboration is essential for success.

The future for EUS-DAD is bright and promising; however, there is still a need for further investigation. The most important information will be obtained from studies comparing the endoscopic and percutaneous salvage modalities of EUS-DAD and PTBD respectively. The next important question to answer would be whether EUS-DAD should be the primary ductal drainage procedure instead of ERCP in select situations, such as distal malignant biliary obstruction. Such information will then form the basis and framework to standardize EUS-DAD recommendations, allowing this procedure to be seamlessly integrated into pancreaticobiliary endoscopy.

It will also be very important to evaluate the learning curve of EUS-DAD, thereby setting standards for training, competency, and ultimately credentialing. The learning needs should be determined based on the experience level of the advanced endoscopist, number of procedures required, referral level of the institution, and availability of ancillary subspecialties. The American Society for Gastrointestinal Endoscopy (ASGE) recommends that, as a minimum, EUS-DAD should be taught in specialized centers with high volumes of EUS and ERCP procedures [10].

In conclusion, EUS-DAD represents an exciting new frontier for therapeutic endoscopy that extends the limits of endoscopic ultrasound, giving patients minimally invasive endoscopic options instead of external drains and surgery. It behooves the advanced endoscopy community to make these procedures safe, accessible, and available to patients who need them.

Publication History

Article published online:
24 June 2021

• References

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