Technique

EUS is performed in a fasting patient. Pharyngeal anesthesia and intravenous sedation are generally used but are not required. Esophagogastroduodenoscopy with a standard endoscope is performed initially because the echoendoscope has limited capabilities as an endoscope The rigid 4.2-cm tip and the oblique viewing optics of the echoendoscope make examination of the mucosa and the lumen more difficult than with standard endoscopes and similar to that with a large diameter side-viewing endoscope. Nevertheless, EUS is as well tolerated as standard endoscopy. After the initial screening endoscopy, the echoendoscope is passed under direct vision to the target area. Intraluminal gas is aspirated to increase contact with the GI wall, which maximizes available acoustic windows. The area to be imaged is brought into focus by filling a balloon surrounding the transducer at the tip of the echoendoscope with approximately 15 mL, water, thus interposing a nonattenuating acoustic coupling medium between the transducer and the surface of the GI wall. If the target area is in the wall itself, water can be placed directly into the lumen for optimal acoustic coupling. The scanning plane is then moved, using scope controls and shaft torque or push-pull maneuvers, to orient the lesion into optimal position. Techniques vary according to the indications and objectives of the examination.

Complication Rate

The complication rate in 42,105 patients surveyed [17] is low (0.05%). Two thirds of upper GI EUS complications occurred in patients with esophageal strictures. In 10 of 13 perforations, esophageal dilation had been performed immediately prior to EUS. Mortality within 30 days of EUS occurred in only 1 of 42,105 patients surveyed and was related to one such perforation. Therefore, aggressive dilation of any esophageal stricture at the time of EUS is not recommended.