French size
Also written as: Fr — French
A measurement system for catheter diameter where each French unit equals one-third of a millimeter.
Full Definition
French size (Fr) is the standard unit for measuring the outer diameter of medical catheters, sheaths, and guidewires used in vascular interventions. One French unit equals 0.33 millimeters or 1/3 mm, so a 6 French catheter has an outer diameter of 2.0 mm. The system was developed by French manufacturer Charrière in the 19th century and remains the global standard for interventional devices. Common sizes range from 4 Fr to 8 Fr for diagnostic catheters and up to 24 Fr for large bore access devices. Smaller French sizes reduce vascular trauma and bleeding complications, while larger sizes accommodate more complex interventional tools.
Usage
Usage note: Always capitalize 'French' and use 'Fr' as the standard abbreviation in medical documentation.
In Context
- "Arterial access was obtained using a 6 French sheath in the right common femoral artery." — Procedure report
- "The patient tolerated the 5 Fr diagnostic catheterization without complications." — Clinical note