Normal values and clinical use of bedside sonographic assessment of postoperative gastric emptying: a prospective cohort study

Abstract

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.