Calculi of the biliary tract and pancreatic duct are a frequent problem encountered by the advanced endoscopist. Indeed, while the majority of these stones can be removed via basic standard techniques of endoscopic retrograde cholangiopancreatography (ERCP), there are occasional situations which require a more advanced approach. This chapter reviews management of complex stone disease of the pancreaticobiliary tract that poses a challenge to the endoscopist, the tools available to deal with these problems, and the ideal ways in which competence in these techniques can be achieved and maintained.

The American Society for Gastrointestinal Endoscopy (ASGE) has adopted the view that the inherent difficulty of an attempted ERCP should be taken into account when using success rates (i.e., selective cannulation, clearance of stones from ducts) as a benchmark to gauge proficiency in a technique. It is therefore essential to be able to recognize potential factors that would make an ERCP fundamentally more difficult. There is a routinely used three‐tier system assigning complexity to ERCP. Standard, grade 1, includes those stones ≤1 cm of the biliary tract that can be treated with standard endoscopic biliary sphincterotomy and removal via retrieval balloon or wire basket. Those classified as advanced, grade 2, involve removal of stones >1 cm. Tertiary, or grade 3 difficulty, encompasses intrahepatic stones or any calculi removed via lithotripsy and all therapeutic pancreatic procedures. It is recommended that management of pancreatic duct stones, as well as any patients with Billroth II anatomy, be generally reserved for endoscopists formally trained in complex ERCP [1, 2]. Current recommendations are that endoscopists with lower levels of expertise should not attempt procedures with difficulty of grade 2 or 3 [3, 4].

Proficiency in standard ERCP techniques such as selective cannulation and sphincterotomy should be attained before attempting to acquire the skills necessary for more advanced procedures. Many reported series have shown that 85–95% of common bile duct stones and 50–75% of pancreatic stones can be successfully treated with basic approaches including sphincterotomy and retrieval of calculi with retrieval balloon and/or wire basket [3, 5]. Training in ERCP and stone removal using these standard techniques are covered more in depth in Chapter 8 of this textbook. Nevertheless, the presence of impacted or adherent stones, intrahepatic calculi, large stones (>10 mm), small‐diameter ducts, strictures, or aberrant anatomy, can be confounding factors which can make removal of pancreaticobiliary stones a very challenging proposition [3–5]. It is recommended that those trainees seeking to acquire the skills needed for treatment of complicated stone disease of the pancreas and biliary tract should pursue a formal additional year of training after a three‐year general gastroenterology fellowship.

As is the case in all aspects of endoscopy, it is essential that the trainee obtain technical as well as cognitive competence in pancreaticobiliary stone disease. Comprehensive knowledge of the anatomy and physiology of the pancreaticobiliary system, as well as common anatomical variants, is vital. In addition, trainees should have a thorough understanding of the indications, limitations, contraindications, and potential complications of various modalities used for complicated stone disease. During training, it is imperative that the trainees acquire knowledge of all the various catheters, guide wires, sphincterotomes, and devices at their disposal, and achieve proficiency in their use [1–4]. Because one specific technique or device is not optimal in all situations, trainees need to be exposed to, and gain proficiency with, a range of tools and techniques designed for the management of difficult stones. Physicians seeking advanced‐tier ERCP training should do so in a high volume center with experienced faculty well versed in these techniques [6]. Numerous studies have shown that procedure volume is an independent predictor of ERCP‐related complications and outcomes. Adverse outcomes are more likely for physicians performing less than 50 ERCPs annually and for centers performing less than 200 ERCPs annually [7]. Advanced therapeutic endoscopists should recognize their own limitations, and readily acknowledge when involvement of surgery or interventional radiology colleagues is necessary. Thus, training in a tertiary academic center with these services readily available is key. In fact, perhaps most important for the trainee is the ability to have a candid appraisal of his/her abilities, and to recognize, for example, when to consider stent placement as a temporizing measure and refer selected patients to an advanced center for further care. This may be the greatest safeguard in avoiding ERCP‐related complications.

Mechanical lithotripsy

When standard techniques fail to clear stones from the biliary and/or pancreatic duct, mechanical lithotripsy can increase the success rate to greater than 90–95%. In cases where the diameter of the bile duct stone exceeds 10 mm, a mechanical lithotripter can often be necessary. An endoscopic biliary sphincterotomy (as described in an earlier chapter) must be performed prior to attempting mechanical lithotripsy. The basic principle of mechanical lithotripsy is first to capture the stone securely, then to close the wires to the extent possible around it. Next, a sheath is advanced over the basket wires, sometimes after replacing the Teflon sheath of the basket with a more firm, metal one. Then, external pressure is applied to the basket wires in an attempt to crush the stone between the wires and the metal sheath. Various devices and methods are available to perform this basic operation and trainees should be familiar with all of them.

When possible, a first lesson is to try to anticipate when mechanical lithotripsy might be needed based on the size of the stone, the size of the duct, and whether any strictures are present. This begins with an accurate interpretation of pre‐ERCP radiologic information such as CT or MRCP; in some circumstances, as in the case of stones proximal to strictures and intrahepatic duct stones, this can provide information that may not be immediately obvious on the initial cholangiogram (Figure 26.1). In general, if there is a stone for which lithotripsy is anticipated, efforts to ensure a sufficiently large sphincterotomy and maximal clearance of smaller stones distal to the larger stone using standard methods before attempting lithotripsy are advisable (Figure 26.2). Trainees should learn that lithotripsy occurs in two circumstances: first, when attempting to clear a stone using standard methods and the stone captured in the basket is found to be too large to be extracted in one piece. In this circumstance, if the stone cannot be dislodged from the basket, then it will need to be mechanically crushed. Second, when lithotripsy is clearly going to be required, a special basket designed to perform through‐the‐scope mechanical lithotripsy should be deployed initially to both capture and crush the stone. Commonly used devices for this technique include the Trapezoid baskets (Boston Scientific Corp., Natick, MA, USA) (Figure 26.3) and the LithoCrush V (Olympus America Inc., Center Valley, PA, USA) (Figure 26.4).

A Dormia basket, a reinforced basket with double length traction wire and a Teflon sheath, is used to capture and then gently draw the stone toward the distal common bile duct (CBD). If the stone cannot be extracted, the handle and Teflon sheath can be removed from the device and replaced with a metal coil with an outer diameter of 6–9 Fr. A separate lithotripter handle with a knurled screw is then employed to draw the basket into the metal coil. The filaments of the basket cut through the stone as they are drawn into the metal coil. It is via this step by which mechanical fragmentation of the stone is achieved. In order to avoid impaction of stone fragments in the distal common bile duct, it is important to advance the basket (with the captured stone) into the middle of the duct prior to stone fragmentation. Once the stone is successfully fragmented, the duct can be cleared using basic ERCP techniques as previously described [5, 8, 9].

Impaction of a “trapped” basket around a stone, fracture of the main operation wire, malfunction of the mechanical lithotripter crank handle, and ductal injury are the most frequently encountered complications of mechanical lithotripsy. These complications have been reported to occur with a varying frequency from 0.8 to 6%. Evaluations of reported complications and their treatments reveal that adverse events occurring during mechanical lithotripsy could be successfully managed endoscopically 94% of the time.

A captured stone that is hard and resists fragmentation can place a great deal of stress on all four branches of the basket, leading to fracture of the traction wire. The use of Dormia baskets with predetermined breaking points at either the base or tip of the lithotripter basket can reduce the risk of fracturing the traction wire. Despite these manufacturing modifications, traction wire fracture can still occur. An extension of the sphincterotomy and attempted dislodgement of the stone with changing of the basket is a frequently attempted solution. If the wire break point is outside the mouth, prompt exchange of the initial 80 cm metal sheath for one of a shorter length of 50–70 cm will often allow for seamless continuation of the lithotripsy procedure [5, 8].

When a stone proves to be too hard to be crushed with the standard Dormia basket lithotripter, a Soehendra lithotripter can be utilized (Figure 26.5). The shaft of the lithotripter is shorter and thicker than the metal coil of the standard lithotripter, providing this with more force by which to break up durable stones. The duodenoscope is removed, and the lithotripter is advanced over the basket under fluoroscopic guidance. The impacted stones are then either crushed or the wires of the trapped Dormia basket are fractured, in either case resolving the impaction (Video 26.1) [5, 8, 9]. It is essential that the trainee be well versed in this salvage method and the operations of the necessary equipment to do so, and it is equally important that the staff be similarly familiar with the technique.

One key to successful training in large stone management is the use of careful planning to avoid more cumbersome and lengthy salvage maneuvers by optimal initial therapeutic choices. Specifically, when the removal of a stone by standard techniques is questionable, initial attempts using a readily deflatable balloon may be favored over a Dormia basket if there is some likelihood that it will get stuck. Deflation followed by sphincterotomy extension or dilation may be easier than resorting to lithotripsy.

The other optimal strategy is to properly anticipate when lithotripsy is likely and in those cases begin directly with a through‐the‐scope (TTS) lithotripsy basket of an appropriately size large enough to capture the stone. Trainees should learn to anticipate which stones are likely to require lithotripsy, and understand how to operate the equipment, including assembling the instruments and accessories and performing the role of the assistant in manipulation of the crushing handle. Even though it is essential for sufficient training of ERCP assistants to remain familiar with this equipment, a trainee must learn to operate it as well in the event that support staff are unavailable or inexperienced with the equipment used (Video 26.2).

Overall, the complication rate of mechanical lithotripsy in the pancreatic duct is nearly three times greater than that seen in the biliary tract. Pancreatic duct stones are harder than bile duct stones, making mechanical lithotripsy particularly difficult in this circumstance. Nevertheless, the most frequently encountered problems seen remain trapped or broken baskets and rupture of the traction wire. Management of these troublesome events is the same as described above for the common bile duct.

While large bile duct stone clearance should be possible in one or two sessions in most instances, trainees need to be aware of the most common reasons why mechanical lithotripsy may fail and when to consider other methods. Problems capturing the stone are often the most likely reason for mechanical lithotripsy failure. In some cases, there is too little room around the stone to pass the lithotripsy basket. A wire‐guided technique may be used to help traverse the giant stone, open the basket, and attempt capture on withdrawal. Another common problem is related to the presence of strictures. Stones larger than 2 cm or bigger than the diameter of the duct at the point of impaction are also particularly difficult to manage in this way, and the trainee should recognize that additional methods such as electrohydraulic lithotripsy (EHL) or laser lithotripsy may be required in these situations (Figure 26.6).

Following successful mechanical lithotripsy of the large stones, trainees must learn to proceed to meticulously clear the duct of all fragments. This can be problematic in the very large‐diameter bile duct, often larger than the 15 mm balloons. On occasion, a special “Flower basket” (Olympus America Inc., Center Valley, PA, USA) with eight wires on the proximal half of the basket may be useful in retrieving small fragments (Figure 26.7). The trainee must be able to assess the fluoroscopic images and determine whether post‐lithotripsy temporary placement of a pigtail biliary stent is necessary to ensure drainage in the event of unremoved residual fragments. Anyone learning to tackle large and challenging stone management should be comfortable with placement of biliary stents in case this is required to ensure drainage in the event of a refractory large stone that will require additional interventions at a later date.

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