EUS-guided portal vein sampling.

EUS provides real-time images of the intramural gastrointestinal tract and adjacent structures that otherwise would not be visible. Given the anatomic proximity to the bowel, accurate identification of the major abdominal vasculature, such as the portal vein, serves as a useful landmark tool for identifying anatomy and staging of malignancies. Recently, increased reports have centered on the utility of EUS-guided vascular access of the portal vein for diagnostic and therapeutic interventions. Pilot and feasibility studies in human patients utilizing EUS-guided portal vein access for circulating tumor cell enumeration and portal pressure gradient monitoring suggest that sampling the portal vein under EUS guidance is safe and effective. This review discusses the rationale and technical aspects of EUS-guided portal vein sampling for diagnostic purposes in gastrointestinal cancer. Understanding the technical aspects of EUS-guided portal vein sampling will be critical to standardizing the procedure, developing new vascular access technologies, and increasing the safety profile.