Evolution of interventional endoscopic ultrasound

Abstract

Endoscopic ultrasound (EUS) has become an indispensable modality for the assessment of the gastrointestinal tract and adjacent structures since its origin in the 1980s. Following the development of the linear echoendoscope, EUS has evolved from a purely diagnostic modality to a sophisticated tool for intervention, with numerous luminal, pancreaticobiliary, and hepatic applications. Broadly, these applications may be subdivided into three categories: transluminal drainage or access procedures, injection therapy, and EUS-guided liver interventions. Transluminal drainage or access procedures include management of pancreatic fluid collection, EUS-guided biliary drainage, EUS-guided bile duct drainage, EUS-guided pancreatic duct drainage, and enteral anastomosis formation. Injection therapies include therapeutic EUS-guided injections for management of malignancies accessible by EUS. EUS-guided liver applications include EUS-guided liver biopsy, EUS-guided portal pressure gradient measurement, and EUS-guided vascular therapies. In this review, we discuss the origins of each of these EUS applications, evolution of techniques leading to the current status, and future directions of EUS-guided interventional therapy.

Keywords: biliary drainage; endoscopic ultrasound; gastrojejunostomy; interventional endoscopic ultrasound; pancreatic pseudocyst drainage.

Figure 1.

Lumen-apposing metal stents

Figure 2.

Endoscopic ultrasound (EUS)-directed drainage of pancreatic fluid collections. (A) Axial computed tomography of a pancreatic fluid collection. (B) EUS allows direct visualization of the pancreatic fluid collection. A 19-gauge needle is used to access the cyst and a guide wire is placed in the cavity. (C) The distal end of the lumen-apposing metal stents (LAMS) is placed in the fluid collection using an electrocautery-enhanced delivery system. Next, the proximal/enteral end of the stent is deployed within the echoendoscope and the scope is gradually withdrawn to allow deployment within the stomach or duodenum. (D) Depending on the location of the LAMS and the need for necrosectomy, the size can range from 10 to 20 mm. The tract can then be dilated over the wire with a through-the-scope balloon to allow increased drainage, direct access, and necrosectomy if needed. (E) Typically, the echoendoscope is removed, a gastroscope is introduced, and the cavity can be directly accessed. (F) Various instruments can be used, including snares, baskets, and nets, to debride the cavity. (G) Necrotic pancreas can be systematically removed from the walled-off collection. (H) Double-pigtail plastic stents are placed within the lumen of the LAMS to facilitate drainage and theoretically decrease risk of bleeding and perforation as the cavity contracts.

Figure 3.

Endoscopic ultrasound (EUS)-directed transgastric endoscopic retrograde cholangiopancreatography (ERCP). (A) In this procedure, the excluded stomach is identified by EUS. The excluded stomach is often described as having a “starfish” appearance. (B) The excluded stomach is accessed using a 19-gauge needle and contrast is injected to confirm location (stomach rugae are visualized fluoroscopically). (C) A stiff wire curled within the excluded stomach. (D) A cautery-assisted catheter is used to deploy a lumen-apposing metal stent, creating a fistulous gastric–gastric tract. (E) The lumen-apposing metal stent (LAMS) is typically dilated between 15 and 20 mm to allow the passage of the duodenoscope. (F) The papilla can then be accessed via passage through the gastric–gastric fistula to allow ERCP.

Figure 4.

Endoscopic ultrasound (EUS)-guided liver biopsy. (A) A 19-gauge fine-needle biopsy (FNB) needle with transgastric access is used to access the liver. Careful attention is made to avoid any vasculature. Following the biopsy, the needle is slowly withdrawn and the tract is examined for any evidence of bleeding. (B) Gross image from a 19-gauge FNB with excellent core samples with intact portal tracts. (C) ×20 image of FNB core samples.

Figure 5.

Endoscopic ultrasound (EUS)-guided portal pressure gradient measurement. (A) A 25-gauge needle is used for transhepatic EUS-guided access to the left hepatic vein. (B) The 25-gauge needle is used for transhepatic EUS-guided access to the portal vein. (C) The compact manometer is placed at the midaxillary line to establish the phlebostatic axis.

Figure 6.

Endoscopic ultrasound (EUS)-guided vascular therapy. (A) The same coils placed transvenously by interventional radiology can also be placed via endoscopic ultrasound. (B) Here we have an endoscopically placed coil in a stomal varices, seen on post-endoscopic abdominal X-ray.