down the TRACHEA into the lungs, usually in the course of administering anaesthetics (see under ANAESTHESIA).
Eustachian catheters are small catheters that are passed along the ﬂoor of the nose into the Eustachian tube in order to inﬂate the ear.
Nasal catheters are tubes passed through the nose into the stomach to feed a patient who cannot swallow – so-called nasal feeding.
Rectal catheters are passed into the RECTUM in order to introduce ﬂuid into the rectum.
Suprapubic catheters are passed into the bladder through an incision in the lower abdominal wall just above the pubis, either to allow urine to drain away from the bladder, or to wash out an infected bladder.
Ureteric catheters are small catheters that are passed up the ureter into the pelvis of the kidney, usually to determine the state of the kidney, either by obtaining a sample of urine direct from the kidney or to inject a radio-opaque substance preliminary to X-raying the kidney. (See PYELOGRAPHY.)
Urethral catheters are catheters that are passed along the urethra into the bladder, either to draw oﬀ urine or to wash out the bladder.
It is these last three types of catheters that are most extensively used.