Despite the surgery-sparing potential demonstrated by interventional endoscopic ultrasound (I-EUS), widespread clinical adoption will require more prospective trials, formalized training programs for endoscopists, and greater support from key stakeholders, according to an AGA white paper.
The publication, which was conceived during a session at the 2019 AGA Tech Summit, addresses the current status and future directions of I-EUS, included EUS-guided access, EUS-guided tumor ablation, and endohepatology.
“We hope this white paper guides those interested in adoption of these technologies into clinical practice and serves as a foundation for future research and innovation in the field,” the investigators wrote in Clinical Gastroenterology and Hepatology.
According to senior author senior author Joo Ha Hwang, MD, PhD, of Stanford (Calif.) University, and colleagues, some of the described techniques are not new, but they have yet to be fully realized.
“Some of these techniques initially were reported more than a decade ago,” the investigators wrote, “however, with further device development and refinement in technique there is potential for expanding the application of these techniques and new technologies to a broader group of interventional gastroenterologists.”
For each I-EUS modality, Dr. Hwang and colleagues reviewed available evidence, and if group consensus was reached, offered practical recommendations.
EUS-guided access
“There has been exponential growth in EUS-guided biliary (including gallbladder) access and drainage procedures, as well as entero-enteric anastomotic procedures in recent years,” the investigators wrote. “This change can be attributed to the availability of lumen-apposing metal stents (LAMS).”
Previous studies have reported promising success rates with LAMS across a variety of EUS-guided procedures, including biliary drainage (equal to or greater than 85%), gallbladder drainage (90%-98%), and gastrojejunostomy (greater than 90%).
Success with other techniques, however, has been mixed.
While LAMS “have gained popularity in the management of pseudocysts and walled-off necrotic collections,” data regarding superiority over plastic stents have been conflicting, and LAMS may increase risk of bleeding in necrotic cavities, wrote Dr. Hwang and colleagues.
“Placement of coaxial plastic stents through the lumen of LAMS has been advocated to try to minimize the risk of complications related to LAMS,” they added.
According to the white paper, EUS-guided pancreatic interventions remain most challenging; both pancreaticogastrostomy and EUS-guided pancreatic rendezvous are associated with technical failure rates up to 40%, and adverse event rates may be as high as 35%.
“Unlike other EUS-guided drainage and access procedures, there has been limited improvement in technology to make EUS-guided pancreatic access easier or safer,” the investigators noted.
Dr. Hwang and colleagues concluded this discussion of LAMS by calling for randomized prospective trials. They also noted the expense of LAMS, which may cost $4,000-$6,000.
EUS-guided tumor ablation
“Because of the close proximity of the gastrointestinal tract to organs such as the esophagus, liver, and pancreas, EUS would appear to be an ideal tool to provide imaging and potentially ablation of benign and malignant lesions in these locations,” wrote Dr. Hwang and colleagues.
But several challenges may stand in the way, they noted, including insufficient endoscope length and working channel caliber, “the tortuosity of the gastrointestinal lumen” and its location relative to some parts of the liver and pancreas, prohibitive tumor characteristics, and cost. In addition, concerns remain for collateral damage to surrounding organs.
“Further studies evaluating the safety and treatment response to ablation of solid neoplasms is required,” the investigators wrote, noting that this may require further development of noninvasive methods to monitor treated lesions.
