Catheter and Sound Sizes

Someone here was interested in what an 11mm urethral sound was in fractional inches, well 10.7 mm is 0.419 inches so it's close to 1/2 inch! A 10mm sounds is 0.3937 inches. Hope that helps! 😉

I used 20 French / 5 or 30 cc catheters for some time. I moved up to 22 French easily, but going to 24 Fr was harder. My urethra, at least the first inch, is naturally just a touch smaller than the 24 Fr catheters. So I had to wear dilators. I prowled around and found medicine droppers that were 8 and 9 mm. A 22 fr is about 23 mm in circumference. A 24 fr is 8mm diameter and about 25 mm circumference and a 9 mm is 28.5 mm circumference. So I forced the 8 mm one in my urethra (somewhat painful) and wore it around for several days. Only masochists should try this. Then I sanded down one of the 9 mm to 8.5 mm and forced that in for a few days, then moved up to a full 9 mm. I found I could insert and wear 24 Fr catheters comfortably after dilating the first part of my urethra.

. . . . A 22 fr is about 23 mm in circumference. A 24 fr is 8mm diameter and about 25 mm circumference and a 9 mm is 28.5 mm circumference. So I forced the 8 mm one in my urethra (somewhat painful) and wore it around for several days. . . .

A 22 Fr catheter is EXACTLY 22 mm in circumference. THAT'S THE DEFINITION.

A 24 Fr is exactly 24/Pi mm = 7.639 mm in diameter.

By definition, the French size is the CIRCUMFERENCE of the instrument.

Take the french size, divide it by 3 and that is the diameter in millimeters.

I checked on answers.com for definition of the French system. http://www.answers.com/topic/french-catheter-scale

They say it's the diameter, 1 FR =.33 mm "For example, if the French size is 9, the diameter is 3 mm. Note: the French scale is equal to the diameter in mm multiplied by three, not the circumference (diameter times π) as is sometimes thought."

I don't care what the lay sites say on the internet.

The definition of the French size is the circumference in millimeters.

Well, I just did a quick random survey of 20 manufacturers of catheter tubing. They alldefine a French unit as 1/3 of a mm.

Speed

[quote author=speedvogel link=topic=1289.msg280584#msg280584 date=1268010072]

Well, I just did a quick random survey of 20 manufacturers of catheter tubing. They alldefine a French unit as 1/3 of a mm.

Speed

[/quote]

That's probably because their sales reps are, and/or think people are to stupid to divide by Pi which is easier to explain than dividing the circumference by Pi to get the diameter. They just say to do it by 3.

A "french unit", and NOT how it is classically described is 1/3.14159mm. (1/3.14159, not 1/3) Sorry to be a pain in the ass, but I'm a stickler. A "French unit" is a millimeter of circumference. EXACTLY.

I stand by my prior statement. The other sources are NOT correct. They are close, but not "right on."

Suzie, could you please site a reference ? At smaller sizes the difference wouldn't be too great, but at larger sizes it would be. The references I've checked all agree that it is 1/3 mm diameter per 1fr increase in size ie 30 fr = 10 mm... not that it really makes all that much difference.

Thanks,

Doc

Don’t know if this helps but I’ve just checked my cath’s (Bard & Rusch) Ch & Fr are the same measurement

[Fr 14 = 4.7mm] --14 divided by 3 = 4.6666666666666666666666666666667 i.e. 4.7mm

[Fr 18 = 6mm] --18 divided by 3 = 6 i.e. 6mm

[Fr 20 = 6.7mm] --20 divided by 3 = 6.6666666666666666666666666666667 i.e. 6.7mm

This info is what is printed on the packaging of each catheter [Fr 14 (4.7mm)] & is represents the outer diameter of the cath.

OK, I did an exhaustive search and found that the "French size" is the diameter times 3. My original 20 year old source was not available stating the "French size" was the circumference. It's a good thing the 4.6% difference isn't deadly. 😳 😳

I retract all my posts where I said the "French size", devised by Charrieire in the 1800's, was the circumference.

Thanks for the correction. All too often people who moderate boards operate on the my way or the highway theory.

Speed 😄

Suzie,

No need to retract - was just curious the reference. A lot of things in medicine come from rather obscure places, and become traditions or standards, where the original source is long forgotten. Sometimes people are able to dig up these obscure sources, and we all get a little history and learn something 😄

Wouldn't have surprised me if your post was correct and the other references were wrong.

Doc

[quote author=docinny45 link=topic=1289.msg280857#msg280857 date=1268111651]

Suzie,

No need to retract - was just curious the reference. A lot of things in medicine come from rather obscure places, and become traditions or standards, where the original source is long forgotten. Sometimes people are able to dig up these obscure sources, and we all get a little history and learn something 😄

Wouldn't have surprised me if your post was correct and the other references were wrong.

Doc

[/quote]

I wouldn't be surprised either. Very often original sources are either lost, not read anymore simply because they are old, "dumbed down" for the masses, or the original source was copied incorrectly and the newer publication became the new official source that was copied ad infinitum. This happens a lot on the internet where you can see word for word copies of one internet article on other sites, each purporting to be the original source.

Well, as I've said in the past, there can be a lot of misinformation posted, but in this case, the difference was negligible.

I'm very interested in these but i'm not sure how the numbers run....

what would b the right size for a beginner..?

Sounds and dilators are usually measured in French units (Fr). Three Fr equals one millimeter. This is close enough for most purposes. We are talking diameter, not circumference. Using a sound slightly larger than the urethral meatus (opening) is usually a good starting point.

Speed

Start small, then slowly increase size slightly if you like. It is not necessary to start with the smallest size. The different sound sets have different numbering and size systems. A reasonable starting point is a souind that is about 14-16 French, or about 5mm in diameter.

Just get a set, that way you will have all you will need.

Here is a link for a variety of sounds:

http://www.healthyandactive.com/industry-medical-supply-urethral-sounds.html?gclid=CJfAwK-0wqACFSURswodmxWbbA

For a woman, I would suggest all except the curved Van Buren because the curve in those is designed for the male urethra shape. As a woman, a straight or very slightly curved sound is what you want. I'd probably also stay away from the Rosebud sounds for most women.

Thanx for the help guys!!!!!

Hey guys! Id like to self cath but I'm unsure of what size cath to use. Any suggestions for a nice size to start with?

Hi Knives i would start with a small 14fr cath then work yourself up but please do your research on safe insertion and use sterile procedure.

Depending on how long you planning on wearing it sometimes a size too small can be worse than too big. The adult urethra can comfortably handle a 16-18fr catheter no problem, if you go to small like a 12-14fr you have the issue that the catheter could move around in your urethra and cause more irritation than if you used a 16-18 french.

If your only going to leave it in for a few hours or so during a play session I'm not sure that this matters as much but definitely go with a size that fits snugly if your looking for extended wear.

Most women can easily handle a 16 or 18 FR with no problems. I play with 16FR because that's what my partner also likes and we order a dozen at a time.

I've had a 20FR triple-lumen inserted and that was also very nice. If you're learning about self-cathing, I would order a 14, 16, 18, and just see what feels the best for you and causes the least irritation. To echo the other posts, the most important thing is aseptic technique. That's much more important than size.

Play On!

LadyDoc

Thanks guys...ill try the 16 fr when I get some play money on hand. Id hate to get a uti the first time in my life because of bad technique.

Knivesreturn I would suggest that you start with the 14Fr for your first time. Normally we take into consideration a person’s body when selecting a catheter size as the diameter gets larger the higher the Fr size as this link indicates

http://www.fraudoktor.com/medical/sizeinfo.htm

smaller is definitely better in this case. As Doc J suggest be careful and ensure strict asepsis to prevent UTI’s; trauma from insertion, balloon inflation can result in excessive and profuse bleeding requiring medical care.

Hope this helps

As a male, a 16 or 18 FR works best for me. I think its typically a matter of personal preference.

It is hoped that more (interested parties) go on to read this Topic to best understand both Catheter & Sounds FR sizing & also take particular note of aseptic techniques to ensure safe practice....Thanks to all above members for explanations as knowledge is a wonderful tool.

Recently, I had to have another dilation by my urologist, it was a 32fr Van Buren

I've recently saw the term "CH" used vs “FR” for catheter size; two instances on Zity, both by members from Germany. Maybe on the German side Zity the “CH” nomenclature is used more often.

The French scale or French gauge system is used to measure the size (outside diameter) of a round catheter. It is most often abbreviated as Fr, but can often be seen abbreviated as Fg, FR or F or CH (Ch) (for Joseph-Frédéric-Benoît Charrière, inventor of the French gauge system). 1 mm = 3 Fr or CH3

Also, didn't realize there were one, two and three way catheters. Both a one way 20F and two way 20F catheter have the same outside diameter but the one-way catheter will have a larger drainage channel than the two-way. Two and Three way catheters accommodate an extra channel(s) for irrigation.

This as been posted before, but:

1 inch = 25.4mm, so ½ inc = 12.2mm

Catheter (or sound) size on Fr scale = (Diameter in mm) * 3

or

Diameter in mm = Catheter size (F) / 3

Example: Fr 16 = 5.3mm ( A Fr 16 is petty much the common size for a man)