The goal of this clinical trial is to learn about the gastric emptying in adult patients that are going to operatin theatre due to an abdominal acute disease, for instance, intestinal obstruction or cholecystitis. This kind of patients are traditionally considered as a full stomach and the induction of anesthesia include rapid sequence intubation (RSI) in order to decrease the risk of aspiration . However, image technologies, like echography, allow the visualization of the stomach and to measure the amount and characteristics of the content lodged in the stomach. This information is vital to decide if RSI is necesary or not. The main question\[s\] it aims to answer are: * What is the percentages of full stomach in patient who come to the operating room due an abodiminal acute disease? * Are different variables, namely, time since diagnosis, use of antibiotics or non steroidal antiinflamatory drugs related with the content of the stomach? Participants will be evaluated with ecography to determinate the amount of content of the stomach before the surgery in the operating room.