You cannot go wrong: choosing digital single-operator cholangioscopy for the diagnosis of biliary strictures

Direct endoscopic visualization of the biliary system is difficult. Cholangioscopy provides an opportunity to directly visualize the bile duct in order to diagnose biliary strictures [1]. Three different cholangioscopy techniques are described including “dual-operator” and “single-operator” cholangioscopy, and the “direct” peroral technique [1].

Use of the traditional “mother – baby” or dual-operator peroral cholangioscope (DOC) requires two endoscopists, one to operate the cholangioscope while the other controls the “mother” duodenoscope [2]. However, cholangioscopy performed using this system is time consuming and cumbersome due to the fragility of the cholangioscope. These systems have now largely been supplanted by the single-operator cholangioscope (SOC), which includes the initial fiberoptic technology-based system and the more recently released digital SOC [1]. Digital SOC has become the standard technique for interventions in the biliary system because of its ease of use and widespread availability [1]. Direct peroral cholangioscopy (DPOC) is performed using an ultra-slim endoscope that can be inserted directly into the bile duct [3]. Although there have been recent changes in technology with prototype multibending scopes to facilitate bile duct intubation, DPOC has traditionally been limited because of difficulty in bile duct intubation and maneuverability [4].

“This review confirms the high accuracy of digital single-operator cholangioscopy when confronted with a challenging patient with biliary stricture.”

There is insufficient evidence to help guide the choice of cholangioscope when confronted with a patient with biliary stricture. In this issue of Endoscopy, Kulpatcharapong et al. [5] present the results of a systematic review summarizing the diagnostic performance of each type of cholangioscope for diagnosis of the etiology of biliary strictures. This study comprehensively reviewed all currently available studies that used cholangioscopes for the diagnosis of biliary strictures and included all prospective studies published as full articles. The authors observed that all the digital cholangioscopes had good image quality. However, diagnostic performance of digital SOC and DPOC demonstrated a higher sensitivity, specificity, and accuracy than those of digital DOC (80 % – 90 %, 89 % – 100 %, and 87 % – 93 %, respectively, for digital SOC; 78 % – 100 %, 73 % – 100 %, and 75 % – 93 %, respectively, for DPOC; 38 % – 100 %, 49 % – 100 %, and 50 % – 100 %, respectively, for digital DOC). In addition, digital SOC showed a slightly higher technical success rate (in terms of insertion technique and scope positioning) at 100 % compared with 82 % – 95 % for DPOC despite being performed by experts in very high-volume centers.

In patients with true indeterminate strictures and inconclusive biopsy results, the authors observed that SOC would be the most appropriate cholangioscope to use because a diagnosis could be accomplished by either the image impression or SOC-guided biopsy. The sensitivity and specificity for diagnosis under SOC-guided biopsy was 76 % – 88 % and 94 % – 100 % compared with the diagnosis under visual impression (sensitivity 90 % – 95 %, specificity 79 % – 96 %). In addition, between the two SOCs, the digital SOC provided a higher negative predictive value than the fiberoptic SOC (89 % vs. 69 % – 84 %), which is not surprising given that high resolution digital technology results in better visualization and higher accuracy.

The clinical implication of this systematic review is clear, as it confirms the high accuracy of digital SOC when confronted with a challenging patient with biliary stricture. The high technical success rate compared with other cholangioscopes also reflects its ease of use. The authors did not investigate whether the use of digital SOC, which is disposable, is cost-effective compared with other cholangioscopes. However, the clinical and economic consequences of SOC use have been evaluated using a decision-tree model for stricture diagnosis based on data derived from two Belgian hospitals [6]. In the model for stricture diagnosis, the use of SOC decreased the number of procedures (–31 % relative reduction) and costs (–€13 000; –5 % relative variation) when compared with endoscopic retrograde cholangiopancreatography (ERCP). SOC performed better than ERCP for the diagnosis of bile duct strictures and reduced the overall expenditure in hospitals in Belgium [6].

Although this systematic review is clinically relevant, there are certain limitations. First, because of the large heterogeneity of the studies, meta-analysis could not be performed. The wide intervals for sensitivity and specificity reflect the significant heterogeneity in the data, which limits the quality of evidence. In addition, no randomized controlled trials comparing cholangioscopes were available. Second, as the authors mentioned, 19 articles were excluded because they provided insufficient data for extraction, which may result in selection bias. Third, in certain subgroups of patients including primary sclerosing cholangitis, the low number of studies limited the ability to determine the best approach. Nonetheless, the data from most studies demonstrated the superiority of cholangioscopes over conventional methods for the diagnosis of biliary strictures. In contrast, a recently published retrospective study questioned the conclusions of the systematic review and found that SOC for indeterminate biliary strictures was found to be inferior to brush cytology, with a low impact on patient management [7]. The limitations of that study were that most of the procedures were performed using the first-generation fiberoptic SOC, which has a reduced image quality resulting in inferior results for both visual assessment and targeted biopsies. In addition, 40 % of the patient population had primary sclerosing cholangitis for which the yield of SOC is not well studied. A recent prospective international multicenter trial comparing digital SOC and ERCP brushings clearly showed that SOC-guided biopsies were effective, with a higher sensitivity compared with standard ERCP techniques in the visual and histopathological diagnosis of indeterminate biliary strictures [8].

Overall, the work by Kulpatcharapong et al. [5] provides support for using digital SOC for the diagnosis of biliary strictures. However, given the good performance of DPOC as well, institutions with expertise in DPOC could continue to use this approach based on local expertise. Future randomized controlled trials are warranted to compare the cost-effectiveness and the performance characteristics of different cholangioscopes. However, designing a trial in cholangioscopy remains challenging because of a lack of both standardized cholangioscopy indications and operator comfort and experience with the various cholangioscopes.

To conclude, irrespective of the type of cholangioscope used, improvements in ease of use coupled with a reduction in costs are needed to drive further utilization of cholangioscopes outside of tertiary referral centers. But until then, you cannot go wrong by choosing digital SOC in the diagnosis of biliary strictures.

Publication History

Article published online:
25 February 2020

• References

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