Free-hand direct insertion ability into a simulated ex vivo model using a prototype multibending peroral direct cholangioscope (with videos)

Biliary Tree Diagnostics: Advances in Endoscopic Imaging and Tissue Sampling

The diagnostic approach to the biliary tree disorders can be challenging, especially for biliary strictures. Albeit the great diagnostic impact of endoscopic retrograde cholangiopancreatography (ERCP) which allows one to obtain fluoroscopic imaging and tissue sampling through brush cytology and/or forceps biopsy, a considerable proportion of cases remain indeterminate, leading to the risk of under/over treated patients. In the last two decades, several endoscopic techniques have been introduced in clinical practice, shrinking cases of uncertainties and improving diagnostic accuracy. The aim of this review is to discuss recent advances and emerging technologies applied to the management of biliary tree disorders through peroral endoscopy procedures.

Advances in Endoscopic Imaging of the Biliary Tree

Direct endoscopic imaging of the biliary tree is increasingly performed by endoscopists since the introduction of digital single-operator cholangioscopy. In parallel, there have been several advances to overcome the challenges associated with direct peroral cholangioscopy with development of multibending cholangioscopes and new devices to enable direct placement of an endoscope into the biliary tree without a supporting duodenoscope. The indications for cholangioscopy are also evolving with newer indications, such as intraductal lithotripsy, foreign body (mostly stent) removal, guide wire cannulation of specific ducts, photodynamic therapy for cholangiocarcinoma, and performance of fluoroscopy-free cholangiography. There has also been progress in image enhancement during cholangioscopy and additional imaging techniques, such as intraductal ultrasound, confocal laser endomicroscopy, and optical coherence tomography.

Novel ex vivo training model for freehand insertion using a double-bending peroral direct cholangioscope

BACKGROUND AND AIM

Several experts of direct peroral videocholangioscopy (D-PVCS) using a conventional ultraslim endoscope have reported its usefulness for the diagnosis and therapy of biliary tract diseases. We have additionally developed a dedicated double-bending D-PVCS technique for freehand scope insertion. In this study, we developed an ex vivo training model for the freehand double-bending D-PVCS technique and compared it with the technique using a conventional ultraslim endoscope.

METHODS

The ex vivo model was made for training using a U-shape insertion pattern. A third prototype endoscope and an ultraslim upper gastrointestinal endoscope were used. Two experts and nine non-experts performed D-PVCS using the freehand technique.

RESULTS

The two experts could not advance the tip of the endoscope to the hilar portion using the freehand technique, but they could achieve technical successful insertion to the hilar portion with the third prototype cholangioscope using the freehand technique alone. The non-experts could not advance the tip of the endoscope to the bile duct using the freehand technique. On the other hand, two (22.2%) non-experts could advance the tip of the third prototype cholangioscope using the freehand technique before the training conducted by the experts. After the training, all the non-experts could advance the tip of the third prototype cholangioscope to the hilar portion.

CONCLUSIONS

The novel ex vivo model using a third prototype cholangioscope was useful for training in the use of the freehand D-PVCS technique.

A review of treatment options for bile duct stones

Approximately 10-15% of bile duct stones cannot be treated using conventional stone removal techniques. For difficult common bile duct stones (CBDS), various endoscopic techniques have been developed. This review covers technical tips and endoscopic treatments including Endoscopic retrograde cholangiopancreatography (ERCP), particularly under Endoscopic ultrasound (EUS) guidance. Areas covered: Literatures about endoscopic treatment for bile duct stone were searched in Pub Med. As novel methods, EUS-guided approaches have also been reported, although long-term results and prospective evaluation are not yet sufficient. Large stones may need fragmentation prior to removal, to prevent stone impaction. To perform fragmentation, mechanical lithotripsy, extracorporeal shock wave lithotripsy or laser lithotripsy techniques are available. Expert commentary: Despite the fact that most bile duct stones can be treated using endoscopic techniques, endoscopists should remind to be able to select the temporary biliary stenting or percutaneous transhepatic cholangiodrainage as an option.

Advances in direct peroral cholangioscopy using an ultrathin endoscope

Some endoscopists have reported the usefulness of direct peroral cholangioscopy for the diagnosis and therapy of bile duct lesions. Advantages of direct peroral cholangioscopy (POC) using an ultra-slim endoscope include use of conventional endoscopy equipment, operation by a single endoscopist, and superior image quality of the biliary tree with easy application of enhanced endoscopy and a large working channel. Although ultra-slim endoscopes are usually used for direct peroral cholangioscopy, direct scope insertion is considerably difficult. Moreover, this technique still has some severe complications and limitations. Continuous development of specialized endoscopes and accessories is expected to facilitate the diagnostic and therapeutic roles of direct POC.

Advanced Imaging Technology in Biliary Tract Diseases:Narrow-Band Imaging of the Bile Duct

Newly introduced direct peroral cholangioscopy and the development of video choledochoscopes have enabled more defined observation of bile duct mucosal lesions with clearer images. Narrow-band imaging (NBI) is a unique endoscopic imaging technology that provides enhanced endoscopic images of surface mucosal structures and its superficial microvessels. Advanced cholangioscopy and NBI are expected to be useful for precise evaluation and correct diagnosis of biliary tract diseases. However, the diagnostic value of advanced bile duct imaging with cholangioscopy requires further evaluation.

Clinical evaluation of a prototype multi-bending peroral direct cholangioscope

BACKGROUND

Although peroral direct cholangioscopy (PDCS) is emerging as an alternative to traditional mother-daughter cholangioscopy, it is associated with high failure rates. The aim of the present study was to evaluate the ability to insert and carry out interventions using a prototype multi-bending PDCS.

PATIENTS AND METHODS

Prospective, observational clinical feasibility study was done in 41 patients with a variety of biliary diseases. A multi-bending PDCS prototype was inserted using a free-hand technique, a guidewire alone, or with a 5-Fr diameter anchoring balloon. Diagnostic and therapeutic procedures were carried out.

RESULTS

The free-hand direct insertion technique failed in all attempted cases (n = 7). Of the remaining 34 cases, successful rate of PDCS insertion into the distal bile duct was achieved by passing the PDCS over a guidewire alone (n = 6) and/or with a guidewire plus anchoring balloon (n = 28) for an overall successrate of 88.2% (30/34). In 13 (92.9%) patients without an underlying biliary stricture, PDCS insertion proximal to the bifurcation was possible. In 25 cases, biliary interventions were attempted including biopsy (n = 13), stone removal (n = 6), stent removal (n = 1), and intraductal electrohydraulic lithotripsy (n = 2) and were successful in 22 (88%). Other than two patients with procedure-related cholangitis with a mild grade of severity, no complications were observed.

CONCLUSIONS

Using a novel multi-bending prototype peroral direct cholangioscope, cholangioscopy had a high diagnostic and therapeutic success rate only when passed over a guidewire and anchoring balloon but not with the free-hand insertion technique. Comparative studies of direct cholangioscopy are warranted.

The role of direct peroral cholangioscopy using an ultraslim endoscope for biliary lesions: indications, limitations, and complications

Advantages of direct peroral cholangioscopy (POC) using an ultraslim endoscope include use of conventional endoscopy equipment, operation by a single endoscopist, and superior image quality of the biliary tree with easy application of enhanced endoscopy and a large working channel. The major diagnostic indications of this system are an evaluation of biliary strictures, filling defects, or unclear findings on cholangiogram or other imaging studies. Therapeutic application using a direct POC system can be broadened by a larger working channel. However, direct POC is difficult to apply in patients with a narrow diameter bile duct, far distal common bile duct lesion, or failed anchoring of the scope with accessories. An air embolism is a rare complication of direct POC but can be a fatal problem. Cholangitis can also occur during or after the procedure. Use of a CO₂ system instead of room air during the POC procedure and administration of antibiotics before and after the procedure are strongly recommended. Continuous development of specialized endoscopes and accessories is expected to facilitate the diagnostic and therapeutic roles of direct POC.