Summary There is increasing evidence that a minority of adults with acute appendicitis have gastric contents, posing an increased risk of pulmonary aspiration. This study aimed to evaluate the proportion of children with acute appendicitis who have gastric contents considered to pose a higher risk of pulmonary aspiration. We analysed point‐of‐care gastric ultrasound data routinely collected in children before emergency appendicectomy in a specialist paediatric hospital over a 30‐month period. Based on qualitative and quantitative antral assessment in the supine and right lateral decubitus positions, gastric contents were classified as ‘higher‐risk’ (clear liquid with calculated gastric fluid volume > 0.8 ml.kg−1, thick liquid or solid) or ‘lower‐risk’ of pulmonary aspiration. The 115 children studied had a mean (SD) age of 11 (3) years; 37 (32%; 95%CI: 24–42%) presented with higher‐risk gastric contents, including 15 (13%; 95%CI: 8–21%) with solid/thick liquid contents. Gastric contents could not be determined in 13 children as ultrasound examination was not feasible in the right lateral decubitus position. No cases of pulmonary aspiration occurred. This study shows that gastric ultrasound is feasible in children before emergency appendicectomy. This technique showed a range of gastric content measurements, which could contribute towards defining the risk of pulmonary aspiration.