How are catheters sized?

The diameter of a catheter is expressed in Charrière. A Charrière is a measurement of small diameters and is denoted by ‘Ch’. One Ch is equivalent to ⅓ mm. Or expressed another way: 1 mm = 3 Ch. 

How many Ch your catheter needs to be will be determined and prescribed by your doctor or specialist. The most commonly used catheter size for women is 12 Ch and for men, it’s 14 Ch.

Advantages and disadvantages of smaller diameter catheters

A larger diameter catheter will enable a faster flow of urine but these can be less comfortable to insert and increase the risk of damage to the urethra. A smaller diameter catheter will slow down the speed of your urine flow. A smaller catheter can be more comfortable to insert as it is more flexible. Curan catheters are available from Ch08 to Ch18.

We have described in detail how to insert a catheter for men and women and explained the procedures in an instructional video.

What is self-dilatation?

Sometimes a catheter will need to have a larger diameter. If you suffer from regularly recurring narrowing of the urethra due to scar tissue, self-dilatation can help you adjust to this. Dilatation means widening. Self-dilatation is the same process as self-catheterisation, but you just use a slightly larger catheter in order to make your urethra wider. 

Self-dilatation can be temporary or permanent. If you need permanent self-dilatation then, as a general rule, you do it at least twice a week. The instructions, guidance and after-care for self-dilatation is exactly the same as for self-catheterisation.