Fig. 1

A Schematic diagram of ultrasonic probe placement. B Ultrasound examination of the gastric antrum. GA, gastric antrum; L, liver; P, pancreas; SMA, superior mesenteric artery; CT, coeliac trunk; AO, aorta. C The CSA measurement is based on the anteroposterior diameter and craniocaudal diameter. CSA, cross-sectional area