Urinary Catheters

Updated: Dec 5, 2022

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Introduction:

Catheters are essentially hollowed tubes that are commonly made of latex or silicone. Urethral catheters are inserted through the urethra into the urinary bladder. Two general categories of urethral catheters are: straight or Robinson catheter and indwelling or Foley catheter.
Catheters are sized by the diameter of the lumen on a French (Fr.) scale of numbers. The larger the number, the bigger the lumen. Small sizes such as 8 or 10 Fr. are typically used in children. Larger sized catheters such as the 14, 16, or 18 Fr. catheters are commonly used in adult patients. 22 or 24 Fr. catheters are usually used in patients with gross hematuria or used for bladder irrigation.

This type of catheter is a single lumen catheter with two eyes or openings near the tip of the catheter. This type of catheter is used for a "straight cath" or in-and-out catheterization of the urinary bladder. It is inserted into the bladder to drain the urine and then removed.

This type of catheter is very useful for men with enlarged prostates. Its curved tip will allow the catheter to pass through the enlarged prostate smoothly. The coudé catheter may cause less trauma in men with enlarged prostates than a straight tipped catheter.
In many cases, after failed catheterization of male patients with a straight tipped catheter, success was achieved when using a coudé catheter. When using the coudé catheter, make sure to keep the curved tip pointing upwards toward the ceiling. One trick in knowing which way the curved tip is pointing is to look at the balloon inflation port or the mark at the end of the catheter. The direction of the balloon inflation port is approximately in the same direction the curved tip is pointing.

This type of catheter has an inflatable balloon near the insertion tip. The balloon is inflated with water after insertion into the bladder. This anchors the catheter inside the bladder.
It is usually pre-connected or connected after the insertion of the Foley catheter to a closed drainage system.
The diameter of the catheter and the size of the balloon are usually indicated on the valve of the balloon inflation port such as 16 Fr. 10 ml.
The size of the balloon may range from 5 ml or 10 ml for regular Foley catheters to 30 ml in large, irrigating catheters.

The three way Foley catheter is similar to the regular two-way catheter except that it has a third channel through which a sterile fluid can be irrigated into the bladder. From the bladder, urine and fluid can drain out through the larger, second channel into the urine drainage bag.