Background The evaluation of preoperative aspiration risk in surgical patients is mainly based on clinical judgement. The aim of this study was to estimate the proportion of surgical patients who undergo rapid sequence induction intubation that have gastric contents and volume which might give a hint that the patient could be at low or high risk of aspiration assessed by gastric ultrasound, and the feasibility of this approach in the clinical setting. Methods In this prospective observational study, seventy-two adult surgical patients who underwent rapid sequence induction intubation underwent gastric ultrasound before induction of anaesthesia. Based on gastric contents and volumes measured in the antrum of the stomach, the findings were categorised into low and high risk of aspiration. Results Evaluation of the gastric contents was possible in 63/72 patients (88% [95% CI: 80–95%]). Among these, the number of patients with indicators for low aspiration risk was 32/63 (51% [95% CI: 38–63%]). The mean examination time was 2 min 50 s (SD ±1 min 16 s [95% CI 2 min 32 s to 3 min 8 s]). Conclusions This small observational study provides hints that half of the patients undergoing rapid sequence induction intubation have, according to gastric ultrasound assessment, not an elevated risk of aspiration. We also showed that a transcutaneous gastric ultrasound examination is easy, fast without time delay and doable immediately before induction of anaesthesia in the operating theatre.