decompression Explanation:Negative pressure exerted through a tube inserted in the stomach removes secretions and gaseous substances from the stomach, preventing abdominal distention, nausea, and vomiting. Instillations in a nasogastric tube after surgery are done when necessary to promote patency; this is not the most common purpose of a nasogastric tube after surgery. Gavage is contraindicated after abdominal surgery until peristalsis returns. Lavage after surgery may be done to promote hemostasis in the presence of gastric bleeding, but this is not the most common purpose of a nasogastric tube after surgery.