Direct examination of the biliary tree with endoscopes has been a challenge since endoscopists began performing endoscopic retrograde cholangiopancreatography (ERCP) in the late 1960s. Direct endoscopic views of bile duct have been described in literature since the 1970s.
The first direct cholangioscopy performed by an endoscopist was probably done unintentionally in a patient with postsurgical anatomy. Indirect imaging, ERCP, and percutaneous transhepatic cholangiography are helpful modalities for examining the biliary tree, but they are limited procedures, particularly with regard to the evaluation and treatment of strictures and bile duct stones.
Cholangioscopy is a noninvasive endoscopic method used for both direct visual diagnostic evaluation and simultaneous therapeutic intervention of the bile ducts. Pancreatoscopy is the direct visual evaluation of the pancreatic ducts. The initial procedures were carried out using a smaller scope (baby scope) inserted through the instrumentation channel of a larger channel therapeutic duodenoscope (mother scope).
Currently available cholangioscopic equipment can be broadly classified into a ‘two-operator system’ or a ‘single-operator system’. The two-operator system includes the conventional “mother and baby” system and needs the active participation of two endoscopists.
Innovation in direct peroral cholangioscopy led to the recent development of single-operator cholangioscopy (SOC) systems (SpyGlass Direct Visualization System from Boston Scientific and the PolyScope system from PolyDiagnost). The catheter-based system attaches to an ERCP endoscope and is preferred over previous methods due to its improved visualization and durability, in addition to being a single-operator system. The currently available fiberoptic baby scopes have an external diameter of 2.8 mm to 3.4 mm with a working channel varying from 0.5 mm to 1.2 mm. They have a single plane tip deflection (up-down) of approximately 90°. These systems are widely available, allow tissue biopsy and can be used for therapeutics. The electronic baby scopes have a charge-coupled device (CCD) video chip which is mounted at the distal tip of the scope.
Single-operator cholangioscopy systems are designed to overcome the limitations of the standard 'mother‑baby' cholangioscopy procedure. As well as needing only a single operator, the SOC system has a 4‑way tip deflection and a single‑use baby endoscope for access and delivery. These systems allow users to visually examine the biliary ducts, take biopsy samples and treat large biliary stones by either electrohydraulic or laser lithotripsy.
A Cholangioscopy system is intended as a first‑ or second‑line alternative to standard ERCP to provide direct visualisation of the biliary system during endoscopic procedures.
As an extension of ERCP, the SOC system enables high-resolution direct imaging, biopsy targeting, and stone fragmentation. A systematic review suggested that biopsies obtained using this SOC system have moderate sensitivity for the diagnosis of malignant biliary strictures.
A recent multicenter study reported high sensitivity and specificity of SOC visual impression and guided biopsies of biliary strictures for the diagnosis of malignancy. The study also reported high rates of complete ductal clearance of bile duct stones using SOC.
Edited by John Sandham.