Normal Values and Clinical Use of Bedside Sonographic Assessment of Postoperative Gastric Emptying: A Prospective Cohort Study

BACKGROUND: GI dysfunction is common after abdominal surgery. However, assessment and diagnosis currently lack objective measurement. OBJECTIVE: The purpose of this study was to evaluate the feasibility and clinical use of bedside sonographic assessment of gastric emptying by measuring the time to complete emptying of a standard volume of ingested water in patients after colorectal surgery. DESIGN: This was a prospective cohort study. SETTINGS: The study was conducted at a single tertiary institution in Sydney. PATIENTS: Healthy volunteers (n = 30) were studied to establish a reference range. Gastric emptying was then measured in patients (n = 39) before and after colorectal surgery. INTERVENTION: Assessment of gastric emptying was performed on days 1 to 4 by measuring antral cross-sectional area every 10 minutes after ingestion of 250 mL of water. MAIN OUTCOME MEASURES: The time to complete emptying of water was used as a surrogate measure of gastric emptying. Information concerning postoperative outcomes, GI symptoms, and recovery was also recorded. RESULTS: The median time to complete emptying of water for healthy volunteers was 20 minutes (range, 10-40 minutes). The study protocol was completed in 30 of 39 patients. The time to complete emptying of water on day 2 had the best discriminatory power to identify patients with ileus (sensitivity, 85.71%; specificity, 82.61%). Gastric emptying was normal in 20 of 30 (67%) patients, with only 1 case of ileus (false negative). These patients had less nausea (p = 0.0003), earlier intake of solid diet (p = 0.001), and shorter hospital stay (p = 0.040) compared with patients with abnormal gastric emptying. LIMITATIONS: Ultrasound is operator dependent with a learning curve. CONCLUSIONS: Bedside sonographic assessment of gastric emptying is feasible and reliable. Assessment of antral contents with a single ultrasound 40 minutes after ingestion of water enables classification of patients into those with normal and abnormal gastric emptying. When performed on postoperative day 2, it has good sensitivity/specificity for discriminating patients with ileus.