Endoscopic Ultrasound in the Patient with Difficult Anatomy

Endoscopic ultrasound (EUS) is most commonly performed as a diagnostic and staging examination. Surgically or pathologically altered anatomy creates obstacles for the endosonographer which may increase risk while decreasing procedural success rate. Traditional echoendoscopes are large, cumbersome, oblique-viewing instruments given the presence of a tip-mounted ultrasound transducer. Hence, maneuvering through altered anatomy may prove challenging if not impossible. Particularly troublesome situations in the esophagus include the presence of a Zenker's diverticulum or malignant stricture. Pancreatic imaging may be compromised after partial gastrectomy or gastric bypass, where pancreatic head imaging may be difficult to impossible. If one can target a pancreatic head mass, EUS-FNA may prove difficult in the setting of malignant venous occlusion with resultant collateral vasculature. This article will discuss various maneuvers and tips to hopefully increase the success rate of EUS examination in these challenging situations.