Exploring Subxiphoid Sagittal Gastric Antrum Views for Quantitative Volume Estimation

Begin by positioning the patient in the supine position. After selecting a low-frequency probe, set the preset to abdominal mode. Place the probe on the patient's subxiphoid region in the sagittal plane, orienting the probe marker in a cephalad direction.

Next, fan the probe from the patient's left to right, until the liver appears on the left side of the screen. Then, visualize a pulsatile aorta in the long axis, deep in the image, followed by the gastric antrum just caudal and deep to the superficial liver edge. Ensure that the abdominal aorta is positioned at the deeper edge of the image.

If the inferior vena cava is observed instead of the aorta, correct the ultrasound beam angle. If the stomach is visible at the pylorus level rather than the antrum, adjust the probe placement by fanning leftward until the aorta becomes visible. Then, identify the muscularis propria of the stomach.

For image acquisition, click Acquire to save a video clip of the current sonographic view. Next, position the patient in the right lateral decubitus. For the quantitative estimation of total gastric volume obtain an image of the gastric antrum at its maximum expansion containing only clear liquids.

Freeze the image. Then activate the trace tool and trace out the cross-sectional area of the gastric antrum along the outer hyperechoic layer of the wall, representing the serosa. Click on Save and use the given formula to estimate the gastric fluid volume.

In the subxiphoid sagittal view, the gastric antrum lies caudal to the liver's tip and superficial to the aorta. In this study, the appearance of the antrum under different conditions as shown, recently consumed clear liquids create a starry night effect due to refracting light, while solid foods result in a hyperechoic air-fluid boundary called the frosted glass appearance. After one to two hours, the air dissipates from the frosted glass image, revealing a hyperechoic heterogeneous content.