Inclusion Criteria:  - Age ≥ 18 years Fasted according to national guidelines Elective surgery ASA physical status I-II Ability to assume both supine and right lateral decubitus position. Able to understand and to sign informed consent  Exclusion Criteria:  - Previous esophagus and gastric surgery, hiatal hernia, gastric cancer. Pregnancy Failure of GUS (defined as failure to visualize the antrum)