What are sizes of Foley catheter commonly used in adults?
The foley sizes (French units) are the diameter of the foley in millimeters times 3, so to calculate the diameter, just divide by 3. Hence a size 15 foley is actually 5 mm in diameter. The commonest sizes placed in adults who have not been catheterized before are 14 and 16; an 18 may be placed if the smaller sizes are leaking. A 14 drains quite slowly, however, and may be prone to clogging if the urine that is being drained has a lot of sediment or immunological material (i.e., pus) in it. For an adult patient who is passing clots, stones, or other material that may block urine flow, a size 22 is commonly used.
In a few cases where a patient has a foley placed for a long period of time, the tissues will begin to stretch, and leakage will dictate a gradual increase in size.
There are 5 types of urinary catheters used today and Foley urinary catheter is one of them. Foley catheter has a self retaining balloon and it is different from Robinson urinary catheter, which has no balloon.
The French scale is used to express the size of catheters, hence 1Fr unit represents a diameter having the size of 0.33 mm. Usually, catheters having sizes between 8Fr and 10Fr are used for children, while catheters having sizes between 14Fr and 16Fr are used for female adults and catheters having sizes between 20Fr and 22Fr are used for male adults.
Commonly, a 16Fr or 18Fr catheter is convenient for a male having a normal urethra of 30Fr, while, for a patient having prostate enlargement, a 20 to 24Fr catheter would be more appropriate. Also, in a patient having gross hematuria, a larger size of catheter is indicated in order to prevent the blockage of the lumen by blood clots, hence, avoiding the urinary retention and urinary tract infections.