ERCP-Based Cell Block: A Potential One-Stop Shop in the Management of Malignant Biliary Obstruction.

Background and aim: Malignant biliary obstruction (MBO) typically results from cancers like pancreatic adenocarcinoma, cholangiocarcinoma, and gallbladder carcinoma, and it often presents at an advanced stage. Diagnostic tools such as ERCP and EUS-FNA are commonly used for tissue sampling, but each has limitations regarding accuracy and cost. This study aimed to compare the diagnostic accuracy and cost-effectiveness of cell block (CB) cytology collected during ERCP-guided stenting with the traditional EUS-FNA plus ERCP-guided stenting approach in patients with unresectable MBO.

Methods: This prospective observational study included 102 patients with advanced unresectable MBO who underwent both EUS-FNA and ERCP-guided stenting with CB sampling. The study evaluated the diagnostic yield of three strategies: CB alone, EUS-FNA alone, and a combination of both methods. A cost-effectiveness analysis was conducted using publicly available reimbursement rates from the public healthcare system to assess potential procedural cost savings.

Results: The diagnostic yield for EUS-FNA (82.35%) was higher than for CB (72.54%), though the difference was not statistically significant (p = 0.23). Combining both methods increased the diagnostic yield to 93.13% (p = 0.04). CB performed better in cases with direct biliary invasion (88.23% vs. 79.41% for EUS-FNA, p = 0.01). A cost reduction of 319.17 € per case was achieved using a CB-only strategy in appropriate cases.

Conclusions: EUS-FNA remains superior for diagnosing extrinsic MBO, but ERCP-based CB offers a cost-effective and reliable diagnostic option, particularly for biliary tract cancers. The combination of both approaches enhances diagnostic accuracy, supporting their concurrent use in specific clinical scenarios, while optimizing costs.