Saturday, September 4, 2010

French Unit


The French scale or French gauge system (most correctly abbreviated as Fr, but also often abbreviated as FR or F) is commonly used to measure the size (diameter) of a catheter. 1 Fr = 0.33 mm, and therefore the diameter of the catheter in millimeters can be determined by dividing the French size by 3:

D (mm) = Fr/3

or

Fr = D (mm) × 3

For example, if the French size is 9, the diameter is 3 mm.

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