Accuracy of Gastric Ultrasound to Diagnose a "Full Stomach". A Bayesian Framework

During surgery, there is a risk that food or liquid in the stomach might be forced back up the throat where it could enter the lungs (aspirate) and result in serious complications or even death. This is why people going for surgery are required not to eat before their surgery. However, in emergency situations it is often not possible to know whether a patient has recently eaten or not. Anesthesiologists have recently developed an ultrasound test to determine if there is content in a patient's stomach and how much. This test involves an ultrasound examination of the abdomen and taking some measurements on the ultrasound screen.

The purpose of this study is to determine how accurate these measurements are. In other words, how good are we at detecting an empty stomach from one that has liquids, or solids in it. You are being asked to participate in this study because we require non-pregnant volunteers in order to answer the aforementioned study question.