- Gastric volume study Methodology For the evaluation of the patients an abdominal CT scan in multislice device will be performed. Diluted oral contrast was administered 3% (amidotrizoate meglumine, sodium amidotrizoate Gastrografin ®) for a maximum distension of the stomach or gastric remnant in order to assess gastric volume or its remnant. Cuts will be made within 45 minutes of ingestion of oral contrast and perform a CT without intravenous contrast supine, including from the tracheal carina to pubic symphysis. Cuts are initiated above the diaphragmatic hiatus to the carina level, in order to evaluate possible migration flows of the gastric remnant as reported in recent publications in this type of surgery.