Gastric emptying scintigraphy: is four hours necessary?

INTRODUCTION: Recommendations for gastric emptying scintigraphy (GES) suggest imaging over 4 hours to better define gastroparesis. AIMS: To determine the value of defining delayed gastric emptying at time points earlier than 4 hours. METHODS: GES was performed with ingestion of a liquid egg white meal with imaging at 0, 0.5, 1, 2, 3, and 4 hours. Patients completed the Patient Assessment of Gastrointestinal Symptoms questionnaire immediately before GES. RESULTS: Of 1499 patients undergoing GES from September 2007 to January 2010 (76.2% were female, mean age of 45.5±0.5 y, 21.3% had diabetes, 9.5% had earlier gastric surgery), 160 (10.7%) had increased gastric retention at 1 hour (>90%), 404 (27%) had increased retention at 2 hours (>60%), 576 (38.4%) had increased retention at 3 hours (>30%), and 629 (42%) had increased retention at 4 hours (>10%). Gastric retention at 4 hours correlated with retention at 3 hours (r=0.890; P<0.001), 2 hours (r=0.738; P<0.001), and 1 hour (r=0.510; P<0.001). Symptoms correlated better with the gastric retention at later time points. The symptoms correlating with gastric retention at 4 hours included early satiety (r=0.170; P<0.01), vomiting (r=0.143; P<0.01), feeling excessively full after meals (r=0.123; P<0.01), and loss of appetite (r=0.122; P<0.01). CONCLUSIONS: Gastric retention at 4 hours correlates well with gastric retention at 3 hours, good at 2 hours, but only fair with gastric retention at 1 hour. Gastric retention at 1 hour may miss 36% of patients found to have delayed gastric emptying at 4 hours. Symptoms (early satiety, vomiting, feeling excessively full after meals, and loss of appetite) correlated better with the gastric retention at later time points.