title: Intraductal ultrasonography for evaluating the patency of biliary metallic stents: correlation with cholangioscopic findings.
abstract: BACKGROUND
  This is the first study to correlate intraductal ultrasonography (IDUS) with cholangioscopy in evaluating the patency of biliary metallic stents.
  
  
  METHODS
  The findings of IDUS (probe 2.0 mm in diameter and 20-MHz frequency) through a percutaneous transhepatic (n = 24) or transpapillary (n = 2) approach were retrospectively reviewed without other information. Criteria for IDUS are as follows: type 1, the inside of the stent is free; type 2, the inner edge is smooth; type 3, the inner edge is irregular; type 4, the inside of the stent is totally occupied; type 5, the solid echo is connected to the outside mass; type 2+D, a hypoechoic line is seen between the bile duct wall and the inside solid component and the inner edge of the bile duct wall is smooth; type 3+D, an irregular hypoechoic line is seen between the bile duct wall and the inside solid component.
  
  
  RESULTS
  In the control group (n = 11), IDUS showed type 1 (n = 9) or type 2 (n = 2). In the occluded group (n = 15), when IDUS showed type 3 or 5, the patients (n = 5) required additional stents (n = 3), microwave coagulation of the tumor (n = 1), or transient external drainage (n = 1). When IDUS showed type 4 (n = 5), after washing, the findings changed to type 2+D (n = 4). When IDUS after washing showed a smooth inner edge (type 2+D), the patients were treated without additional stents more frequently than the other groups (eight of nine vs. two of six), a significant distinction (p < 0.05).
  
  
  CONCLUSIONS
  IDUS is useful in assessing the patency of metallic stents. When the inside of the stent is totally occupied, however, examination after washing is necessary.
authors.affiliation: Department of Gastroenterology, Jichi Medical School, Yakushiji, Tochigi 329-0498, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Tamada
authors.forename: T
authors.initials: T
authors.lastname: Tomiyama
authors.forename: A
authors.initials: A
authors.lastname: Ohashi
authors.forename: S
authors.initials: S
authors.lastname: Wada
authors.forename: Y
authors.initials: Y
authors.lastname: Satoh
authors.forename: T
authors.initials: T
authors.lastname: Higashizawa
authors.forename: Y
authors.initials: Y
authors.lastname: Gotoh
authors.forename: K
authors.initials: K
authors.lastname: Ido
authors.forename: K
authors.initials: K
authors.lastname: Sugano
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001652:Bile Ducts / Q000000981:diagnostic imaging* / Q000473:pathology; D016145:Endoscopy, Digestive System; D005260:Female; D006801:Humans; D008297:Male; D008670:Metals; D008875:Middle Aged; D012189:Retrospective Studies; D015607:Stents; D014463:Ultrasonography
chemical_list: D008670:Metals