Anesthesiologists try to avoid complications with significant peri -operative morbidity and mortality such as bronchoaspiration in patients requiring a surgical procedure under anesthesia. Currently, this is achieved based on experts recommendations from the American Society of Anesthesiologists. However, there are tools like ultrasound that allow assessment of gastric content and volume. This tool allows to individualize each patient and base the decisions objectively. The investigators will assess gastric content and volume by ultrasound in patients who have fasted and require surgery at two University Hospitals.

Inclusion Criteria:

• Adults ≥ 18 years
• perioperative fasting time between 8 and 14 hours
• American Society of Anesthesiologists status I, II, III
• Scheduled surgery

Exclusion Criteria:

• Abdominal pathology surgical emergency
• Unable to adopt right lateral decubitus position
• Altered gastrointestinal tract anatomy excluding hiatal hernia
• Body mass index greater than 40
• Patients on enteral nutrition probe or with nasogastric probe
• Pregnancy

Men and women 18 years or older requiring surgery with complete preoperative fasting (more than 8 hours but less than 14), ASA I-III.