Difficult common bile duct stones: still “difficult” or just... “different”?

“Difficult biliary stones” represents a broad and vague definition that encompasses a wide range of conditions requiring different treatment strategies. What should be considered “difficult” in the treatment setting of bile duct stones?

First, and most obvious, the stones themselves! Barrel-shaped or square, multiple and piled up, impacted in the common bile duct (CBD) or cystic duct, large with a dimension of more than 10, 15, 20 mm – generally, all these features could characterize hard-to-retrieve stones.

Second, we must consider the shape, diameter, and angulation of the CBD, and how these features may increase the difficulty of endoscopic retrograde cholangiopancreatography (ERCP). Is the access, or exit, of the CBD adequate for the retrieval of that type of stone? [1] [2] [3].

Furthermore, previous upper gastrointestinal surgery could definitely add complexity to the procedure. The use of enteroscopes or nondedicated devices, although conceptually comfortable or familiar, are not less complex. Alternatively, endoscopic ultrasound-assisted approaches, such as the endoscopic-directed transgastric ERCP, are making their way as promising options. A laparoscopic approach for access to bile duct stones could also be considered.

Moreover, we have to manage a range of different clinical situations. A scheduled ERCP on Monday morning, with adequate time allocation, a well-known clinical and imaging history, and a dedicated room with experienced staff, is quite different from an urgent ERCP in a patient with the same CBD stones, 30 years older, with severe cholangitis, on a Friday afternoon. Would your approach be the same? Usually you would prefer to reach CBD clearance (obviously), but sometimes you should only try to achieve effective biliary drainage. It depends on many aspects: your experience, the indication, and whether or not you are working within your comfort zone.

The strength of this study lies in the effort to identify some pre-endoscopic predictive values of complete stone clearance at the second ERCP. This could help doctors in decision making, sending patients to tertiary referral centers rather than attempting to perform a second ERCP approach with a high risk of repeated failure.”

In this issue of Endoscopy, Jang et al. have addressed a common, critical, and debated topic: “Factors associated with complete clearance of difficult common bile duct stones at the second endoscopic retrograde cholangiopancreatography after a temporary biliary stenting” [4]. In this multicenter, retrospective study in a cohort of 85 patients who underwent a second ERCP after plastic biliary stenting, the authors found that 7-Fr rather than 10-Fr stents were useful for complete clearance of difficult CBD stones and stone clearance was significantly higher in patients with a stone size reduction of > 5 mm. Moreover, in a multivariate analysis, older male patients as well as patients with initial stones > 25 mm had a lower clearance rate, and ursodeoxycholic acid administration, as well as the number of stents placed, did not show a significant association with the complete clearance rate.

The strength of this study lies in the effort to identify some pre-endoscopic predictive values of complete stone clearance at the second ERCP. This could help doctors in decision making, sending patients to tertiary referral centers rather than attempting to perform a second ERCP approach with a high risk of repeated failure.

However, there are several drawbacks of the study that limit the ability to draw definitive conclusions. First, the study had a retrospective design and a small number of included patients. Second, the methods used at the second procedure did not involve either endoscopic papillary large balloon dilation (EPLBD) or single-operator cholangioscopy (SOC)-assisted lithotripsy, which are currently considered as standard approaches in this setting of patients. Third, and perhaps more important, the outcome definitions, such as how complete duct clearance was evaluated, were not clearly specified.

With the advent of EPLBD we are now able to effectively and easily treat conditions that were considered complex in the past. Nevertheless, how difficult or risky is it to perform? When performing EPLBD, is a fibrotic sphincter as safe as a normal one? Could a previous sphincterotomy or the presence of a peripapillary diverticulum present any additional risks?

An extensive number of papers have addressed this debatable argument of “difficult common bile duct stones,” by analyzing various approaches, as well as factors associated with clearance and recurrence. Recently published European Society of Gastrointestinal Endoscopy guidelines represent a cornerstone, answering virtually all of the above questions separately, but not in combination or all together [5].

In our endoscopic armamentarium, we now have many treatment approaches, each for a specific setting. However, there is still poor evidence regarding which “strategy” to apply. For instance, it is easier to understand when EPBLD should be performed instead of standard sphincterotomy alone, and guidelines strongly recommend, with high-quality evidence, the use of EPBLD in cases of difficult biliary stones; however, it is less easy to distinguish which procedure is best between mechanical lithotripsy or cholangioscopy-assisted, laser or electrohydraulic lithotripsy.

Recently, a randomized clinical trial published by Bang et al. demonstrated that SOC-assisted laser lithotripsy outperforms EPLBD for the treatment of difficult biliary stones, as a rescue approach after standard extraction (balloon or basket). A cost-analysis evaluation showed the usefulness of this strategy considering overall success rate [6]. Moreover, in a previously published paper by Deprez et al., a decision model for SOC-assisted extraction was proposed, and demonstrated a reduced number of procedures and costs when performed as the initial procedure rather than as a secondary procedure [7].

So, what should be considered the correct strategy? Stepwise in the same session? Upfront approach with advanced tools? How long should you perform mechanical lithotripsy after EPLBD or SOC-lithotripsy for large and multiple biliary stones before placing a plastic stent and scheduling for an additional procedure/intervention?

Regardless of the above evidence, there is still debate regarding which approach is most effective. Different pre-endoscopic prognostic scores and risk stratification methods have been proposed as useful tools when faced with other complex clinical situations in daily practice, such as upper gastrointestinal hemorrhage, acute pancreatitis, etc.

Evaluating pre-endoscopic variables linked to history, stones, and clinical parameters, matched with post-ERCP results, will be a challenge that we cannot evade. Diligent work on this topic could lead to promising results – the introduction of a comprehensive, evidence-based, and clinically approved score that can classify “difficult biliary stones” into “different biliary stones.”

Publication History

Article published online:
27 May 2020

• References

• 1 Trikudanathan G, Navaneethan U, Parsi MA. Endoscopic management of difficult common bile duct stones. World J Gastroenterol 2013; 19: 165-173
• 2 Kim HJ, Choi HS, Park JH. et al. Factors influencing the technical difficulty of endoscopic clearance of bile duct stones. Gastrointest Endosc 2007; 66: 1154-1160
• 3 McHenry L, Lehman G. Difficult bile duct stones. Curr Treat Options Gastroenterol 2006; 9: 123-132
• 4 Jang DK, Lee SH, Ahn DW. Factors associated with complete clearance of difficult common bile duct stones after temporary biliary stenting followed by a second ERCP: a multicenter, retrospective, cohort study. Endoscopy 2020; 52: 462-468 DOI: 10.1055/a-1117-3393.
• 5 Manes G, Paspatis G, Aabakken L. et al. Endoscopic management of common bile duct stones: European Society of Gastrointestinal Endoscopy (ESGE) guideline. Endoscopy 2019; 51: 472-491
• 6 Bang JY, Sutton B, Navaneethan U. et al. Efficacy of single-operator cholangioscopy-guided lithotripsy compared with large balloon sphincteroplasty in management of difficult bile duct stones in a randomized trial. Clin Gastroenterol Hepatol 2020; DOI: https://doi.org/10.1016/j.cgh.2020.02.003.
• 7 Deprez PH, Duran RG, Moreels T. et al. The economic impact of using single-operator cholangioscopy for the treatment of difficult bile duct stones and diagnosis of indeterminate bile duct strictures. Endoscopy 2018; 50: 109-118