Being Creative with Old Tools: The Dilating Balloon as a Weapon Against Difficult Bile Duct Stones

One of the joys of practicing therapeutic endoscopy is the resourcefulness that is often required to solve the most difficult challenges with existing or available tools that are not necessarily designed for the problem at hand, with large or difficult-to-remove bile duct stones as prime examples. While 90 % of stones can be removed via endoscopic retrograde cholangiopancreatography (ERCP) using conventional methods and instruments (e.g., biliary sphincterotomy and balloon or basket extraction), approximately 10 % are “difficult” either because of their large size, impaction in the bile duct, the presence of bile duct strictures or relative stenoses distal to the stone(s), or of a massively dilated or distorted bile duct confounding stone capture [1]. In these circumstances, more advanced technologies and sophisticated techniques have been developed (see Table 1), but are often more expensive and unavailable at smaller medical centers.

Table 1 Current techniques/devices available for bile duct stone extraction

The use of balloon dilation for the assistance of bile duct stone extraction was first described in 1983 by Staritz et al. [2] who used inflatable balloon catheters for ampullary dilation (ABD). In 2004, however, a randomized, controlled multicenter study reported significantly increased morbidity and mortality in patients undergoing ABD compared with endoscopic biliary sphincterotomy (EBS) [3], reducing enthusiasm and increasing the concern for using larger-sized balloons in the biliary system. In the late 2000s, however, several reports, including one randomized, control trial [4], were published on post-sphincterotomy balloon dilation (PSBD) to facilitate the extraction of large bile duct stones, renewing the popularity of this technique, as it was safe, effective, inexpensive, and utilized tools readily available in most endoscopy units.

In this issue of Digestive Diseases and Sciences, Park et al. [5] have, for the first time, described the use of a similar balloon within the bile duct as a clever form of mechanical lithotripsy when more conventional means of bile duct stone extraction have failed. This study reported a single-center, single-endoscopist experience in seven patients who had large or impacted bile duct stones that could not be extracted with balloons, baskets, or mechanical lithotripsy [5]. The authors described “endoscopic balloon dilation lithotripsy” (EBDL), which involves inflating a standard 10–12 mm CRE-[controlled radial expansion] wire-guided balloon within the bile duct, adjacent to the offending stone for 60 s under fluoroscopic guidance in order to achieve stone fragmentation. The authors’ results are impressive—100 % success rate with no serious complications in any patient, but all the more impressive considering that the patients and stones involved presented exceptional technical challenges even for the most advanced endoscopists: mean stone size >3 cm (2.1–5.2 cm) and mean bile duct diameter >3 cm (1.5–5.2 cm). The authors argue that the greatest advantage of this technique, besides its efficacy and apparent safety, is that it uses widely available and inexpensive tools, in contrast to alternatives such as SPYglass cholangioscopy and electrohydraulic or laser lithotripsy.

There are, however, several limitations to the study and technique reported by Park et al. that need to be taken into consideration before the average endoscopist embraces and attempts EBDL. It is, for example, unclear whether all patients first underwent PSBD, and if so, to what size the ampulla was dilated, since PSBD is safe and effective [6], with its early use often obviating the need for mechanical lithotripsy, laser lithotripsy, or EHL (see Fig. 1).

Fig. 1

Suggested order and the degree of difficulty for endoscopic extraction of difficult bile duct stones

Most obvious is that this is a study of only seven patients by a single, very experienced biliary endoscopist. Selection of appropriate patients, balloon size, and correct positioning of the balloon within the duct is likely to be critical for performing this technique safely and effectively, and likely requires an experience and comfort level that the majority of Western biliary endoscopists lack. In the United States, biliary endoscopists in the community are very hesitant to perform PSBD and therefore are even less likely than their counterparts at tertiary medical centers to attempt EBDL. Consequently, the endoscopists more likely to adopt EBDL are in most circumstances likely to have EHL or laser lithotripsy capabilities readily available and may be more likely to employ them prior to attempting EBDL. In the discussed study, three ERCPs were required for ductal clearance in 4 of the 7 reported patients, who had in turn undergone prior ERCPs, obscuring the total number of biliary procedures required to treat their stones. Furthermore, although the authors used cholangiography to confirm complete stone clearance, there was no mention of follow-up duration to document that these patients were indeed stone-free. Most EHL and laser lithotripsy are performed via cholangioscopy (direct visualization), and there are data supporting that cholangioscopy is more accurate in detecting residual stones or fragments after lithotripsy than is conventional cholangiography, particularly in very dilated ducts [7, 8]. For the above reasons, the cost-effectiveness of this small study cannot be calculated.

Despite the above criticisms, this technique appears noteworthy and promising. Indeed, since initially reviewing this manuscript, I performed EBDL in two patients who would have met inclusion criteria for the discussed study. In both patients, EBDL was easy to perform, successful, and without complication. For gastroenterologists performing ERCP who are comfortable performing PSBD, I would therefore recommend considering adding EBDL as a complementary technique for dilation-assisted stone extraction when difficult bile duct stones are encountered (see Fig. 1). After all, if PSBD is being performed in a patient, the same balloon can then be used for EBDL without any increase in cost. It is clear that larger, multicenter studies are needed before EBDL can be routinely recommended as an alternative to EHL or laser lithotripsy, but in the mean time, I encourage my fellow ERCPists to continue being creative and thinking outside the proverbial box.