CT scans can be used to calculate gastric volumes. In patients with adhesive small bowel obstruction, the initial gastric volume could guide the indication for nasogastric tube placement. The objective of this study was to evaluate a quick method for calculating gastric volume on CT scan by measuring two diameters of the gastric antrum, inspired by the “quick” gastric volume ultrasound measurement.

From January 2020 to January 2023, gastric volumes on contrast-enhanced CT scans performed upon admission for patients with adhesive small bowel obstruction were measured using two methods. First, by manual gastric contouring, and second, by measuring two diameters at the antrum and calculating the area, performed by two different operators.

A total of 139 patients were included. The mean age was 71 years, 43% of patients were male, the mean BMI was 27, and the surgery rate was 18%. The average gastric volume was 381cc, with the highest recorded volume being 2254cc. The percentage of patients with a gastric volume>300cc was 41%. The mean volume collected by the nasogastric tube during the first 24hours was 1300cc. The average time to measure gastric volume by manual contouring was 365seconds (6.08minutes) vs. 45seconds using the two-diameter measurement technique. The correlation coefficient between the two measurement methods was 0.88, showing strong correlation. The intra-observer correlation coefficient was 0.78.

Quick measurement of gastric volume on CT could help guide nasogastric tube use in patients with adhesive small bowel obstruction, limiting the use of poorly tolerated invasive procedures.