Sensitivity and Specificity of Gastric Ultrasonography in Determination of Gastric Contents

Perioperative pulmonary aspiration (PPA) is a major cause of morbidity and mortality. During anesthesia, airway reflexes become depressed, placing patients at risk of PPA. Gastric ultrasonography (GUS) can be used to qualitatively differentiate between solids, liquids, and empty gastric contents. The purpose of this study was to determine the sensitivity and specificity of GUS in identifying gastric contents after participants were randomly assigned to consume 1 donut, drink 360 mL of water, or remain fasted (n=60 each group). Ultrasonography was performed by a blinded scanner, and qualitative findings were recorded by 2 sonography examiners and the primary scanner. Findings from the water group included a sensitivity of 95% to 100% and specificity of 87.5% to 90% for identification of liquids. Interrater reliability results yielded an intraclass correlation coefficient (ICC)=.781 for the solid group; ICC=.950 for the fluid group; and ICC=.761 for the fasted group. Statistically significant differences were found for the effect that body mass index classifications had on sensitivity and specificity of GUS for predicting gastric content. Results of this study demonstrated that GUS is highly sensitive, specific, and reliable with low false-positive and false-negative rates in the identification of fluid gastric content.