Intraductal ultrasonography for evaluating the patency of biliary metallicstents: correlation with cholangioscopic findings

Background: This is the first study to correlate intraductal ultrasonograph y (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 frequenc y) through a percutaneous transhepatic (n = 24) or transpapillary (n = 2) a pproach were retrospectively reviewed without other information. Criteria f or IDUS are as follows: type 1, the inside of the stent is free: type 2, th e inner edge is smooth; type 3, the inner edge is irregular; type 4, the in side 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 d uct 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 = II), IDUS showed type 1 (n = 9) or type 2 (n = 2). In the occluded group (n = 15), when IDUS showed type 3 or 5, th e patients (n = 5) required additional stents (n = 3), microwave coagulatio n of the tumor (n = 1), or transient external drainage (n = I). When IDUS s howed 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 patie nts were treated without additional stents more frequently than the other g roups (eight of nine vs. two of six), a significant distinction (p < 0.05). Conclusion: IDUS is useful in assessing the patency of metallic stents. Whe n the inside of the stent is totally occupied, however, examination after w ashing is necessary.