Diagnostic ERCP

Abstract
Interventional cardiologists have developed a system for grading the technical difficulty of coronary artery procedures. In comparison, ERCP outcomes are reported in terms of success and complication rates, and there is at present no objective scale for quantifying the technical difficulty of ERCP. Schulz et al. [ 1 ] developed this type of grading scale for technical difficulty in ERCP, and evaluated it retrospectively during 1997 then prospectively during 1998. The grading ranges from 1 (simple diagnostic ERCP) to 5 (very advanced ERCP). For example, common bile duct stenting or extraction of more than three common bile duct stones was classified as 4. Removal of one or two small stones was graded 2, and all forms of pancreatic therapy 5. If an ERCP was previously unsuccessful, a B modifier was added to the grade (e. g., a diagnostic cholangiogram after an unsuccessful attempt at another center was graded 1B). Procedures involving more than one intervention received the highest applicable grade. In 1997, Schulz et al. carried out 231 ERCPs [ 1 ]. The success rate was 94 % for grades 1 to 4B, and 74 % for grades 5 and 5B (P < 0.05). The morbidity rate was higher in grades 5 and 5B than in grades 1 to 4B (P < 0.05). In 1998, 187 ERCPs were performed and analyzed prospectively. The success rate was 96 % for grades 1 to 4B and 65 % for grades 5 and 5B. The morbidity rate was higher in grades 5 and 5B (8. 7 %) than in grades 1 to 4B, but the difference was not statistically significant. The authors stated that more prospective studies and also input from expert endoscopists are mandatory before this scale can be adopted for general use. Prior sphincterotomy or stent placement in the desired duct should also be included in the scale. The authors believe that this type of scale could allow meaningful comparisons to be made among endoscopists and centers, and could be helpful for purposes of ERCP training, credentialing, and billing. The success rate is highly variable from one center to another, depending on the disease entities being treated, the availability of dedicated accessories, well-trained staff, and the skill of the endoscopists concerned. Choudari et al. [ 2 ] conducted a prospective study which shows that if an attempt at ERCP is unsuccessful, referral to another center at which there are advanced ERCP skills is a good option. A total of 562 patients were referred to the Indiana University School of Medicine for ERCP after having undergone a previous unsuccessful attempt to inject the clinically relevant duct. The overall success rate for visualizing the desired duct was very high at 96.4 %, although a standard 5-Fr catheter or a manometry catheter was used in 59 % of cases. The main factors possibly contributing to the failure of the prior ERCPs were duodenal diverticulum, overhanging duodenal folds, and Billroth II anatomy. ERCP identified a cause or potential cause for the symptoms in 86 % of patients, but it should be noted that sphincter of Oddi dysfunction and pancreas divisum accounted for 51 % and 14 %, respectively, of the final diagnostic findings. The overall complication rate was 10.1 %, and the mortality rate was 0.2 %. Sphincter of Oddi dysfunction and pancreas divisum are still controversial disease entities in Europe. Despite the high success rate and the fairly low morbidity rate in this series - due to the authors' experience - the use of alternatives such as endoscopic ultrasonography or MRCP should also be an option in these cases. However, as the authors state, this paper emphasizes the role of large referral centers with available resources and expertise. Whether to use a standard catheter (e. g., a metallic tip catheter) or a sphincterotome as a first-intent accessory to cannulate the common bile duct is still a question. The sphincterotome has a few theoretical advantages: the angle of the end of the catheter can be varied and made more acute by modifying the wire tension, and the stiffness of the sphincterotome allows better directional control. On the other hand, the standard catheter is thinner and floppier. Schwacha et al. [ 3 ] conducted a randomized study in 100 consecutive patients to compare the success rate and safety of selective common bile duct (CBD) cannulation using a guide-wire sphincterotome without a guide wire, with a standard catheter. They confirmed the opinion of some experts: the primary success rate of selective common bile duct cannulation was significantly higher with the sphincterotome (84 %) than with the standard catheter (62 %). If CBD cannulation failed even after four or five attempts, it was regarded as unsuccessful, and the alternative technique was then used. Thus, in patients in whom the standard catheter primarily failed, the use of the sphincterotome increased the total success rate to 94 %, while in patients in whom the sphincterotome primarily failed, the use of the standard catheter increased the total success rate to 88 %. The complication rates, and in particular the frequency of pancreatitis, did not statistically differ between the two groups. The authors therefore recommend using the sphincterotome before resorting to precut techniques. More and more frequently, experts are recommending the use of the sphincterotome as the primary accessory for CBD cannulation, as the increasing rate of therapeutic ERCP favors the primary use of the sphincterotome in order to avoid catheter exchange. The authors did not use guide wires in this study, in order to prevent potential trauma to the papilla. However, hydrophilic guide wires could have increased the success rate of selective CBD cannulation in this series, and further prospective studies should be performed with this material. Some experts find guide wires so helpful that they cannulate the bile duct using fluoroscopic rather than endoscopic guidance.