A retention (indwelling) catheter is ordered to permit continued drainage of the urinary bladder without repeated catheterization.

The catheter commonly used is a self- retaining urethra catheter (Foley type). This tube has a double lumen: one lumen is for drainage and the other is for inflation of the retention device (a small balloon at the tip of the catheter).

The retention balloon is inflated with a measured amount of sterile water following its placement in the bladder.  When a retention catheter is used, provision is usually made for bladder drainage by means of drainage tubing connected to a plastic drainage bag.

Following insertion of the catheter, it is a nursing responsibility to set up and maintain the drainage system. Aseptic technique in maintaining urinary drainage is required since the patient is exposed to a source of chronic irritation from the indwelling catheter and is therefore more susceptible to any source of infection.