Although ERCP has been the standard technique for the nonsurgical diagnosis and management of pancreaticobiliary disease over the past several decades, this method relies on indirect visualization via fluoroscopic imaging of the biliary tree,5,6 and ERCP diagnosis of pathologic lesions via brush cytology and/or intraductal biopsy can have poor sensitivity.7 Consequently, many biliary lesions are indeterminate, which led to the development of a technique for direct visualization of the biliary tree for diagnosis and intervention—direct cholangioscopy.
Since the 1980s, several different strategies have been used for direct cholangiopancreatoscopy, including mother-daughter systems (insertion of a smaller cholangiopancreatoscope through a large-channel duodenoscope), and percutaneous cholangiopancreatoscopy through a mature T-tube tract.6,8 However, these strategies are limited by the need for 2 endoscopists, the fragility of the equipment, prolonged periods of time required for maturation of the T-tube tract, and poor visualization capabilities.8
Innovation in direct peroral cholangioscopy led to the development of the single-operator POCPS SpyGlass System SpyGlassTM Direct Visualization System (Boston Scientific Corporation), which was cleared for clinical use in the U.S. in 2005.9 The system consists of a catheter (SpyScope™) that is inserted through a standard working channel therapeutic duodenoscope.9 For visually directed biopsies, disposable biopsy forceps (SpyBite™) can be inserted into the SpyScope working channel.4
Recent technological advances have enhanced the visualization capabilities of the SpyGlass System using high-resolution digital technology, an improvement that also allows for a smaller image transmission cable, thereby improving maneuverability of the catheter tip. This new digital SpyGlass system—SpyGlass DS Direct Visualization System, made available for clinical use in 2015—has 2 dedicated irrigation channels and 4-way tip deflection.9,10It includes a simplified setup using an integrated light source and camera (Figure 1). The device eliminates the need for reprocessing of the optical bundle as is required with the legacy SpyGlass.4 In addition, the digital optics along with improved suction and irrigation abilities enable substantially improved visualization.4
Potential diagnostic applications for the SpyGlass DS System include evaluation of indeterminate strictures; diagnosing indeterminate filling defects in the bile ducts observed during ERCP imaging; preoperative mapping of the precise location and extension of tumors of the pancreatobiliary tract; visual evaluation and biopsy of biliary stenosis; diagnosis of intraductal neoplasms; hemobilia; and detection and characterization of stones. Therapeutic applications include visually guided treatment of biliary stones that have otherwise failed extraction using conventional ERCP techniques, management of residual or impacted stones, removal of migrating biliary or pancreatic duct stents, and challenging cases of guidewire placement.2,3,11 In particular, the accuracy and operational efficiency of the SpyGlass™ DS System for the diagnosis and management of biliary and pancreatic disease is supported by extensive clinical data.