​Surgery Definition - What are the indications for the insertion of the gastrointestinal tube?

​What are the indications for the insertion of the gastrointestinal tube? 
The indications for the insertion of the gastrointestinal tube may include for feeding purposes where fine bore NGT is used, to empty the content of the stomach as pre operative measure to prevent aspiration and to rest the bowel in the case of pancreatitis.