title: Mechanisms of biliary stent clogging: confocal laser scanning and scanning electron microscopy.
abstract: OBJECTIVE
  Endoscopic insertion of plastic biliary endoprostheses is a well-established treatment for obstructive jaundice. The major limitation of this technique is late stent occlusion. In order to compare events involved in biliary stent clogging and identify the distribution of bacteria in unblocked stents, confocal laser scanning (CLS) and scanning electron microscopy (SEM) were carried out on two different stent materials - polyethylene (PE) and hydrophilic polymer-coated polyurethane (HCPC).
  
  
  METHODS
  Ten consecutive patients with postoperative benign biliary strictures were included in the study. Two 10-Fr stents 9 cm in length, one made of PE and the other of HCPC, were inserted. The stents were electively exchanged after 3 months and examined using CLS and SEM.
  
  
  RESULTS
  No differences were seen between the two types of stent. The inner stent surface was covered with a uniform amorphous layer. On top of this layer, a biofilm of living and dead bacteria was found, which in most cases was unstructured. The lumen was filled with free-floating colonies of bacteria and crystals, surrounded by mobile laminar structures of mucus. An open network of large dietary fibers was seen in all of the stents.
  
  
  CONCLUSIONS
  The same clogging events occurred in both PE and HCPC stents. The most remarkable observation was the identification of networks of large dietary fibers, resulting from duodenal reflux, acting as a filter. The build-up of this intraluminal framework of dietary fibers appears to be a major factor contributing to the multifactorial process of stent clogging.
authors: Dept. of Gastroenterology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors: A M
authors: AM
authors: van Berkel
authors: J
authors: J
authors: van Marle
authors: A K
authors: AK
authors: Groen
authors: M J
authors: MJ
authors: Bruno
mesh_terms: D000328:Adult; D001652:Bile Ducts / Q000473:pathology*; D018441:Biofilms; D003251:Constriction, Pathologic; D004043:Dietary Fiber; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D020959:Polyethylene; D011140:Polyurethanes; D015607:Stents
chemical_list: D004043:Dietary Fiber; D011140:Polyurethanes; D020959:Polyethylene