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.

The pulmonary aspiration of gastric contents is a serious anesthetic complication with high associated morbidity and mortality. Its incidence is estimated to be between 0.1% and 19% of cases of general anesthesia. It is associated with admission to intensive care units, prolonged mechanical ventilation, and mortality, which can reach up to 5%. On the other hand, it accounts for 9% of anesthesia-related death). Given this, in patients at risk of aspiration, such as non-compliance with fasting or acute abdominal pathology, rapid sequence induction is routinely used. However, this technique is not without risks, being associated with episodes of desaturation, hyperkalemia, among others. Therefore, it is reasonable to question the widespread use of this technique in all urgent surgeries for acute abdominal pathologies, based solely on the pathophysiological concept that inflammation and pain could be associated with delayed gastric emptying and therefore a higher risk of aspiration, especially in high-risk populations for desaturation and difficult airway, such as pediatric patients or pregnant women.

The use of ultrasound for determining gastric content is a feasible tool to assess the risk of aspiration. The best results have been obtained using curved transducers, with the patient in a semi-sitting or right lateral decubitus position, where the evaluation of the gastric antrum has shown better sensitivity in detecting content in patients with prolonged fasting. Multiple studies have been conducted in adult and pediatric patients, including obstetric and obese patients, for whom the technique could be more challenging, achieving high sensitivity and specificity in determining gastric content with ultrasound based on standardized measurements of the antrum. The purpose of this study is to describe the percentage of patients that have full stomach just befor the induction of the anesthesia and to evaluate if preoperatory treatments and time since the diagnosis are related with the gastric emptying.

Inclusion Criteria:

• Adults patients
• Emergency surgery
• Diagnosis of Acute Abdomen

Exclusion Criteria:

• Younger than 18 years old
• No posibility of adopt lateral decubitus.