Advances in Endoscopic Ultrasound, Part 2: Therapy

Abstract

Initially developed in the 1980s, EUS has seen increasing use in the past decade. First introduced as a diagnostic modality, it has enabled the endosonographer to visualize details of anatomy and pathology not previously attainable by most gastroenterologists or radiologists. The indications for EUS are expanding – forcing gastroenterologists to ‘think outside the lumen’ about possible therapeutic implications. The most common indications for EUS include diagnosis of solid and cystic lesions of the pancreas, subepithelial luminal pathology, biliary tract pathology and cancer staging. Established therapeutic indications include pseudocyst drainage and celiac plexus neurolysis (CPN) for pain from pancreatic adenocarcinoma. The advent of echoendoscopes with larger accessory channels, which can accommodate larger diameter devices, has led to experimentation in EUS-guided surgical therapy and natural orifice transgastric endoscopic surgery (5,6). The growing interest in EUS is best illustrated by the emerging therapeutic capabilities of this technology (Table 1). The introduction of linear echoendoscopes in the 1990s enabled the endosonographer to trace the path of the needle during FNA. FNA has allowed for diagnostic tissue and fluid sampling, but has also guided the development of newer therapeutic techniques. Pancreatic pseudocyst drainage is a common and well-known indication for EUS. However, an increasing number of case reports and case series have reported the successful use of EUS for the drainage of a variety of fluid collections accessible from the stomach, duodenum or rectum. These include hepatic, subphrenic and pelvic abscesses, bilomas, postoperative fluid collections, infected gallbladders and infected pancreatic necrotic collections. EUS is well-suited for drainage of fluid collections and abscesses not easily amenable to computed tomography (CT) or ultrasound-guided percutaneous approaches due to intervening bowel, bladder and vascular structures (7–20). TABLE 1 Therapeutic indications for endoscopic ultrasound