Assessment of residual gastric volume by ultrasound prior to upper endoscopy: a prospective cohort study

Pulmonary aspiration is an adverse event with high morbidity and mortality. Despite fasting for > 8 hr, some patients still have residual gastric volume and are thus at risk of aspiration. We aimed to determine the accuracy of gastric ultrasound in assessing residual gastric content in patients undergoing upper gastrointestinal endoscopy.

In a prospective cohort study, we performed gastric ultrasound immediately before upper gastrointestinal endoscopy in a sample of 294 patients. We categorized the ultrasound results as high risk of aspiration when the fluid volume was > 1.5 mL·kg⁻¹ or when there was thick/solid content. We applied Spearman’s test to determine the correlation between aspirated volume and ultrasound-estimated volume using three mathematical models. We assessed the method’s accuracy by calculating its sensitivity and specificity.

We included 282 patients in the analysis. The incidence of residual gastric contents was 5%. There were no aspiration events. Prokinetic use (relative risk [RR], 7.5; 95% confidence interval [CI], 1.9 to 29.1; P < 0.01), previous stroke (RR, 4.0; 95% CI, 1.2 to 13.6; P = 0.02), and male sex (RR, 3.3; 95% CI, 1.2 to 9.4; P = 0.02) were significantly more frequent among those with residual gastric content. The ultrasonography’s specificity and sensitivity to predict gastric content at risk of aspiration were 100% and 77%, respectively, with a positive predictive value of 100% and a negative predictive value of 99%.

Ultrasonography was an effective way to assess residual gastric content, which can help improve patient safety.