Background: Tumor involvement to the orifice of the cystic duct (OCD) is a risk factor for cholecystitis after metallic stent (MS) placement.
Objective: ERCP and intraductal US (IDUS) were used to assess tumor involvement to the OCD.
Design: A prospective consecutive study.
Setting: The University of Tokyo Hospital, Japan.
Patients and interventions: Between January 2003 and May 2007, 34 patients with resectable malignant biliary obstruction underwent an ERCP and an IDUS before preoperative biliary drainage.
Main outcome measurements: ERCP and IDUS findings were confirmed via a histopathologic analysis of surgical specimens.
Results: An ERCP showed that the cystic duct was opacified in 22 of 34 patients (64.7%). Eight patients were diagnosed with OCD tumor involvement. In the remaining 12 patients, tumor involvement was impossible to evaluate via an ERCP. An IDUS identified tumor involvement to the OCD in all 34 patients. Tumor involvement to the OCD was diagnosed in 12 patients, including 4 patients with previously negative results during an ERCP. Tumor involvement was confirmed by histopathology of surgical specimens. The sensitivity and specificity of detection were 66.7% (8/12) and 63.6% (14/22), respectively, via ERCP, and 100% (12/12) and 100% (22/22), respectively, via IDUS.
Limitation: The small sample size.
Conclusions: IDUS, in addition to ERCP, provides an accurate evaluation of tumor involvement to the OCD in patients with malignant biliary obstruction.