The introduction of a tube into a body orifice. The term usually is used to mean the introduction of a tube through the mouth or nose into the windpipe in order to maintain an adequate air passage into the lungs. It is carried out in general anesthesia, in cases of unconsciousness due to other causes, and in cases where the breathing is obstructed.

Gastric intubation, the passage of a tube into the stomach through the esophagus, is necessary in some cases of obstruction to the esophagus and in some cases of paralysis of the swallowing mechanism. It is used in cases of intestinal obstruction so that the contents of the stomach can be aspirated. It is also used to wash the stomach out in cases of poisoning.