Urinary catheters are flexible tubes that help drain urine from the bladder. If you’re experiencing urinary retention or other bladder problems, your doctor may use one to provide relief.
But catheters come in a variety of sizes. So, how do doctors know which one to use? Catheter sizes are measured using the French catheter sizing system (Fr). The Fr number tells you the catheter’s outer diameter, with a higher number indicating a larger diameter.
Choosing the right French size is essential for efficient drainage, comfort, and to avoid complications.