The full form of NPO in medical is Nothing by Mouth, also abbreviated as Nil per OS. Also called complete bowel rest, nil by mouth, or nulla per Os, it is used when a liquid-based diet is only recommended to the patient. Simply put, NPO stands for no food or drink. In some cases, it encompasses no oral medications. More than half of patients experience fasting for some period of time while hospitalized.
The main objective of NPO guidelines is preventing aspiration pneumonia. For example, it is suggested for patients undergoing general anesthesia who have weak swallowing musculature or gastrointestinal clogging, gastrointestinal bleeding, or acute pancreatitis. Excessive consumption of alcohol leading to severe external bleeding or vomiting may also incur NPO guidelines for a specific period of time.
NPO guidelines generally allow between 6 and 12 hours prior to surgery through recovery suite discharge. If a long-acting medication or oral medication is suggested, the duration may be longer. However, since the duration of NPO is too long for the disease, complex exceptions are made for small amounts of water intake if an IV drip is not used.