Staging of cholangiocarcinoma: the role of endoscopy.

The main question for staging is resectability, which is reliant on vascular, longitudinal, and metastatic spread. Today, accurate staging of perihilar tumors is achieved by non-invasive diagnostic investigations. Direct cholangiography has been the gold standard as a diagnostic procedure in recent decades. Endoscopic retrograde cholangiopancreaticography (ERCP) often only shows the ducts below the obstruction, and visualization of an obstructed part of the biliary tree is often not possible. Direct cholangiography reveals no information about local tumor extension, lymph nodes, or vascular involvement. Because of the given limitations, potential complications (cholangitis, sepsis) associated with direct cholangiography and reduction of the accuracy of subsequent cross-sectional imaging studies, these invasive techniques should only be used in the case of palliative interventions. Endoscopic ultrasonography-guided fine-needle aspiration (EUS-FNA) can be used to assess the nature of biliary strictures and to derive information about the extent of periductal disease and the presence of lymph node metastases. In a study by Fritscher-Ravens, 44 patients with hilar strictures underwent EUS-FNA. The overall diagnostic accuracy, sensitivity, specificity, positive and negative predictive values were 91% (95% CI, 78.4-96.3%), 89% (95% CI, 73.3-96.8%), 100% (95% CI, 63.1-100%), 100% (95% CI, 88.8-100%), and 67% (95% CI, 34.9-90%), respectively. The planned surgical approach was changed in 27 of 44 patients. In 15-20% of cholangiocarcinoma, patients with unremarkable abdominal imaging studies have metastatic lymph node involvement according to EUS evaluation. Due to the risk of peritoneal seeding, however, EUS with FNA is not recommended in patients still with a potential curative tumor.