Multi-Planar Ultrasonographic Assessment of Gastric Volume

Authors: Liu H et al.

Anesthesiology, February 23, 2026

Summary

This prospective observational study evaluated whether the ultrasonographic measurement plane influences the accuracy of predicted gastric volume (GV) when assessing aspiration risk preoperatively.

Point-of-care gastric ultrasound is increasingly used to estimate gastric volume and stratify aspiration risk. However, different sonographic planes are commonly used—most frequently the abdominal aorta (AA) plane and the inferior vena cava (IVC) plane—and their equivalence has not been clearly established.

Study Design

196 volunteers were included in final analysis.

Protocol:

1. Baseline gastric ultrasound performed after fasting (low GV state) at:

   • Abdominal aorta (AA) plane

   • Inferior vena cava (IVC) plane

2. Participants then ingested apple juice (2.3 ml/kg).

3. Repeat gastric ultrasonography performed (high GV state).

4. Predicted ingested volume (PIV) was calculated as:
   Predicted GV after ingestion – baseline predicted GV.

5. Agreement between predicted ingested volume (PIV) and actual ingested volume (AIV) was assessed for:

   • AA plane

   • IVC plane

   • Higher-measured plane

   • Lower-measured plane

The study also examined detection rates for high aspiration-risk classification.

Key Findings

1. AA and IVC Measurements Differ Significantly
   In both low and high gastric volume states, measurements at the AA and IVC planes differed significantly (P < 0.001).

2. Plane Selection Affects Accuracy
   Only the plane that produced the higher measured gastric volume showed:

• No statistically significant difference between predicted and actual gastric volume

• The smallest measurement bias (−4.27 ml, P = 0.076)

3. Lower-Measured Plane Underestimated Volume
   Models using the lower-measured plane showed greater bias and reduced agreement with actual ingested volume.

Interpretation

This study demonstrates that measurement plane is not interchangeable when applying predictive models for gastric volume estimation.

The authors conclude:

• Using the higher-measured gastric volume plane improves accuracy

• Model development and validation should account for measurement plane

• Differentiation between AA and IVC planes may enhance predictive reliability

Clinical Implications

For anesthesiologists performing preoperative gastric ultrasound:

• Avoid assuming AA and IVC measurements are equivalent

• When applying established volume prediction models, use the plane yielding the larger antral cross-sectional area

• Standardization of measurement plane may reduce variability in aspiration-risk stratification

What You Should Know

1. Plane choice matters. AA and IVC planes produce significantly different volume estimates.

2. The higher-measured plane is more accurate. It aligns more closely with true ingested volume.

3. Underestimation risk exists. Using the lower-measured plane may falsely classify patients as low aspiration risk.

4. Future models should standardize plane selection.

5. This supports refinement of gastric ultrasound protocols for perioperative aspiration risk assessment.

Key Points

• Prospective study of 196 volunteers.

• Significant differences between AA and IVC measurement planes.

• Higher-measured plane showed strongest agreement with actual gastric volume (bias −4.27 ml).

• Measurement plane selection directly affects prediction accuracy.

• Standardization may improve gastric ultrasound reliability.

Thank you to Anesthesiology for allowing us to summarize and share this important study advancing precision in preoperative gastric ultrasound assessment.