Went to get blood drawn for some lab work and the technician commented that I was dehydrated and my blood was flowing too slowly (he had to take 9 vials of blood) and so since the last few tubes couldn’t be filled, he resorted to opening the cap of some tubes (full of blood) and pouring it into the other tubes.
I’ve already sent messages to the lab and am waiting to hear back, but doesn’t this cause air contamination or whatever to get in, or cause the blood to start clotting since it was exposed to open air? Just wanted to hear from some medical Dopers. I’d never seen a technician do this before.
I imagine that it depends on what you’re testing for. But I don’t think that it’s air, per se, that would be the contaminant, but bacteria or spores or the like that might be in the air.
Generally not. The tubes have vacuum to help suck in blood, not to prevent the blood from contacting air.
I suppose there’s a small risk of picking up some stray dust carrying viruses or bacteria, but if they are testing the blood promptly, for normal blood test stuff, it shouldn’t matter.
Fwiw, a million years ago when i worked in a lab doing research, one of my coworkers did tests on patient blood. She opened the tubes and used a clean pipette to move some of it to the vessel in which the actual test was done. So that’s comparable to the exposure your blood got, I’d think.
Different tubes contain different “stuff” like anticoagulants and such. There are situations where combining partial draws from multiple tubes could affect the ratio of additive to blood.
Orange top vacutainer tubes (the most commonly used brand) contain clot by activator and serum separating gel. The sample is being used to get serum, and combining multiple tubes is fine.
Blood doesn’t need to be exposed to air to clot.
Certain tests require clotted blood since they’re testing what’s in the serum and everything else is just in the way.
It’s the additives in the various tubes that matter, not exposure to air. A lavender or blue topped tube should never be poured into another tube of a different color for instance. Pouring blood from the same color top tube (except blue) is usually ok. Every now and then a nurse here at the hospital tries to pour from a lavender into a gold top, thinking that if they do it fast enough it’ll be ok. Nope. It messes up the chemistry results in a spectacular way and I always will know what they did.
Signed, a Medical Technologist
Thanks. I’m a bit concerned since I wasn’t paying attention to the tube caps but it is possible that some were not gold/orange. The phlebotomist seemed a pretty “eh, whatever” careless guy in the way he did things so I wouldn’t put it past him to put lavender into gold.
I was assuming he used the same type (cap color) of tubes. Yeah, you don’t want to mix the different types.
I find that it helps to be both hydrated and salted. My blood pressure is higher when i eat salt, and it results in faster blood draws. A pickle and a big glass of water can help me give blood. Although I’ve gotten better at it in recent years mostly, I’m better at holding still and the phlebotomist gets a cleaner stick.
Isn’t one of blood’s jobs exchanging oxygen and carbon dioxide with nearby air? If you cared about these, wouldn’t exposing it to air change results? I’m thinking of the arterial draws for blood gases especially.
I assume any test for the oxygen content etc. is done immediately, at the patient I havea little laser thingy I stick my finger into, from back in the Covid times. No blood draw required.
