Point-of-care ultrasound in the acute abdomen and gastrointestinal emergencies: An evidence-based guide and the case for standardisation

Figure 5 Gastric point-of-care ultrasound for aspiration-risk stratification. A: Representative antral image acquired by the authors, showing the gastric antrum with the anterior liver as the acoustic window; antral cross-sectional area is obtained from the anteroposterior and craniocaudal diameters as described in the text; B: The Perlas qualitative grading system (grades 0-2) with the corresponding aspiration-risk category, and the emergency-department and fasting-reference antral cross-sectional area cut-offs. Each threshold applies only to the body position and population in which it was derived, and the full set of published thresholds and their dispersion is shown in Figure 2B. All cited studies relate antral measurement to gastric volume; none relates it to aspiration or to any other patient-centred outcome. RLD: Right lateral decubitus.