Smallest gauge for blood draw?

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Hi there,

I'm not a nurse, but a vet tech. I need to practice my venipuncture technique and was wondering about whether an insulin needle could be used? Or would the gauge need to be larger due to the viscosity of blood?

Thanks for any advice, my potential guinea pigs will appreciate it!!

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Specializes in Public Health, TB.

I would check with your lab. Usually the gauge needs to be big enough to prevent lysing the red blood cells. I think a 20 is about as small as you can go for a human.

I am not sure you would get much of a flash with an insulin needle, and it may clot rather quickly.

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Specializes in NICU.

We use 24s in neonates.

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It's a combination of the needle (or catheter) gauge and whatever is pulling the pressure. A good flowing 24g IV and 3ml syringe yields perfectly acceptable results for my peds patients. Directly transferring into the vacutainer tube (using its own pressure) is also a good way to avoid lysis.

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Specializes in Pedi.
I would check with your lab. Usually the gauge needs to be big enough to prevent lysing the red blood cells. I think a 20 is about as small as you can go for a human.

I am not sure you would get much of a flash with an insulin needle, and it may clot rather quickly.

We definitely draw blood from 24 g IVs when placed or 25 g butterfly needles in pediatrics. You can't use a 20 g on a baby.

I agree that an insulin needle is not appropriate for a blood draw, it's meant for a subq injection.

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Specializes in NICU, ICU, PICU, Academia.

We used 24/25 in PICU.

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Specializes in ED.

I used 25g needles on rats when I was a vet tech. I also ran all of my own labs so I had to get it right the first time or create more work for myself. An insulin needle is not appropriate for blood draws and I would advise practicing with the biggest gauge you can. That way if you have to go smaller it's not a problem. Why not consult the vet you work for?

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Thanks everyone!!

I guess I could have clarified. I used to be a vet tech and I'm applying for my dream job at a clinic and really need to practice my technique.

I appreciate the advice!

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We use 24s in neonates.

I wish everybody would understand this concept.

"well, I was taught you need at least a 20g to administer blood". Aaargh. I usualy ask how they would give blood to a baby,

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Specializes in NICU.
I wish everybody would understand this concept.

"well, I was taught you need at least a 20g to administer blood". Aaargh. I usualy ask how they would give blood to a baby,

To be fair, I doubt adult volumes would run through a 24g.

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To be fair, I doubt adult volumes would run through a 24g.

I don't thing that the volume is the issue- I think it is the rate. No question a 24 can be used for a transfusion- but I would like to see an authoritative source regarding the rate.

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Specializes in NICU.
I don't thing that the volume is the issue- I think it is the rate. No question a 24 can be used for a transfusion- but I would like to see an authoritative source regarding the rate.

Well, yes. I meant an adult volume of blood in the time blood requires, which would by necessity be a high rate.

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