Cardiovasc Intervent Radiol (1994) 17:127-132 Review Article CardioVascular and Interventional Radiology 9 Springer-Verlag New York Inc. 1994 Metallic Biliary Endoprostheses Andreas Adam Department of Radiology, 2nd Floor, Guy's Tower, Guy's Hospital, St. Thomas' Street, London, SE1 9RT, UK Abstract In patients with obstructive jaundice caused by unre- sectable malignant tumors, biliary endoprostheses in- sterted percutaneously or endoscopically can provide excellent palliation. Conventional plastic stents are as- sociated with a relatively high rate of occlusion caused by biliary sludge. Migration is another significant prob- lem. Self-expandable, metallic stents can be inserted percutaneously via a small transhepatic track but ex- pand to achieve a relatively large internal diameter. This minimizes the problem of occlusion due to en- crusted bile and reduces the rate of reintervention. Mi- gration rarely occurs. Metallic stents have also been employed in the management of recurrent benign bili- ary strictures unsuitable for surgery. In those patients in whom the frequency of radiological intervention is unacceptably high, such endoprostheses can provide a means of preventing restenosis. Key words: Biliary strictures--Obstructive jaun- dice-Metallic stents Inoperable malignant obstructive jaundice is being pal- liated increasingly by insertion of biliary stents either endoscopically or percutaneously. Initially only the percutaneous method was available. When endoscopic insertion of relatively large caliber stents became fea- sible this method assumed a dominant role in the non- operative management of patients with malignant biliary obstruction. The main reasons for the increasing popularity of the endoscopic method were the ability of the endoscopists to complete the procedure in a sin- gle session and the apparently less traumatic nature of endoscopic insertion compared to the percutaneous ap- proach [1]. Some of the evidence which has been pre- sented as proof that endoscopic biliary stenting is safer and more effective than percutaneous stenting has been Correspondence to: A. Adam, M.D. questioned [2] but it is undeniable that the endoscopist continues to play a dominant role in this field. The ad- vent of expandable metallic stents has introduced new considerations which should be taken into account when deciding the best method of treatment for an in- dividual patient. The use of metallic stents in benign biliary stric- tures is more controversial. However it is becoming increasingly apparent that in difficult clinical situations in which surgery would present major technical prob- lems or would place the patient' s life at risk these stents may represent an acceptable solution. This article aims to outline the main features of metallic stents and to suggest a strategy for their use. Stent Design There are two broad categories of metallic endopros- theses: 1. Balloon-expandable (Palmaz, Strecker). 2. Self-expandable (Wallstent, Gianturco, new version of Strecker). The main advantage of metallic stents is that they can be introduced in their contracted state through a very small caliber track and achieve a large lumen fol- lowing expansion. The large caliber is associated with a lower frequency of occlusion due to bile encrustation. As metallic endoprostheses in their expanded state are partially embedded in the bile duct wall migration is not a frequent problem. The Wallstent endoprosthesis in addition has sharp ends which anchor the stent in position. Balloon-Expandable Metallic Stents These devices are mounted on angioplasty balloons prior to insertion; the rigidity inherent in this carrier may make it difficult to advance the stent around acute