During this exam, a flexible tube containing a small transducer about the size of your index finger is guided down your throat.

CNN: Heart murmurs

In bladder instillation, the prescription medication dimethyl sulfoxide, or DMSO, (Rimso-50) is placed into your bladder through a thin, flexible tube (catheter) inserted through the urethra.

CNN: Interstitial cystitis

He'd spent eight years developing a special kind of Foley catheter--a flexible tube inserted into the bladder of hospital patients and disabled people to drain urine--that staved off inevitable infections.

FORBES: Magazine Article

The laparoscope is a flexible controllable tube, with a camera and a bright light at the end, which allows the surgeon to see inside a patient's body.

BBC: Hospital installs new keyhole equipment

They ended up producing a flexible catheter tube that goes a bit of the way up the nostrils, then a guide wire is inserted into the targeted sinus. (In live patients this is done via an endoscope and fluoroscope.) A balloon catheter is advanced over the guide wire and positioned against the blocked ostium.

FORBES: Balloon Therapy