Malignant obstruction of the extra-hepatic bile duct often leads to jaundice and pruritus and occasionally results in cholangitis and bacteremia. Pancreatic cancer accounts for a large proportion of patients presenting with malignant extra-hepatic biliary obstruction. Most pancreatic cancers are unresectable at presentation, and palliation, including biliary decompression, is often a goal of therapy. Over the last decade, biliary decompression with endoscopically-placed stents during endoscopic retrograde cholangiopancreatography (ERCP) has largely replaced surgical bilioenteric diversion. Biliary decompression via endoscopic stenting alleviates cholestatic symptoms and improves quality of life. When compared to surgery, endoscopically placed plastic stents result in decreased morbidity and a trend towards decreased 30 day mortality. However, surgery is associated with a lower risk of recurrent biliary obstruction.
Stent diameter is an important factor in determining duration of biliary luminal patency. All plastic biliary stents will ultimately occlude due to deposition of bacterial biofilm. The original plastic biliary stents were 7 French (Fr) in diameter, with a patency rate of about 4 weeks. With increases in the size of the working channel of duodenoscopes, the limiting factor in what diameter stent can be deployed, 10 Fr stents were developed, with patency rates of approximately 15 weeks (3-4 months). Until recently, the largest stent that could be deployed with the current endoscopic technology using a conventional duodenoscope of acceptable outer diameter was 11.5 Fr; the limited available data suggest that these stents do not offer more prolonged luminal patency interval compared to 10 Fr stents.
In the early 1990s, self-expandable metal stents (SEMS) became available for use in palliation of malignant biliary obstruction. Once deployed, SEMS achieve larger diameters than plastic stents, which results in a longer median patency interval of approximately six to eight months.\[3, 6, 9-12\] Although effective, metal stents are eight to ten times more costly than plastic stents.
Recently, a large working channel duodenoscope with an acceptable outer diameter has been developed. This prototype duodenoscope allows passage of larger stents, which the investigators have successfully placed in select cases using this prototype. This duodenoscope, manufactured by Olympus Medical Systems Corp., is FDA approved.
The investigators hypothesize that, with the substantially increased luminal diameter, larger plastic stents will provide more prolonged relief of obstructive jaundice in patients with malignant distal common bile duct strictures. If this proves to be true, larger plastic stents may constitute a cost-effective alternative to SEMS, especially in health care systems that cannot afford SEMS.
