Order of Draw for Labs - Concerns / Looking for Your Opinion / Expertise

[aroelisland]

Hi all, I'm an NTC in training and have experience in Integrative Oncology (but am not a nurse or phlebotomist) - and am still learning the ropes, especially when it comes to labs and proper procedures. Through my studies, I've now learned that there is an "Order of Draw" for lab work - probably common knowledge in this community, but new to me!

That has led me to this, "Oh sheesh" personal moment - and I hope you don't mind this personal question?

A family member (following a cancer diagnosis that she's now in remission from) gets about 40 lab tests every six months from Quest Labs. One of those is Plasma VEGF. Several rounds of tests ago, her doctor suggested she get VEGF drawn "first" by the phlebotomist because apparently VEGF levels can be impacted if it's closer to the last tube of blood drawn. So, for the past several rounds of labs, we've requested VEGF Plasma to be drawn first, and then proceed as normal. Our phlebotomist has never mentioned it at the lab, or voiced concern with it.

However, as mentioned, I just realized there's something called an "order of draw"... so now my concern is that we've somehow contaminated other tubes of blood by requesting VEGF to be drawn first (which I believe is a lavender top tube)?

I've since read extensively online about whether or not "order of draw" is truly important, and have found several articles that say that while it's good practice (and if you can, "why not do it"?), contamination risk is extremely minute and inconsequential. And that "order of draw" was initially established many years ago on a small sample group, and has since been shown to be inconsequential (though still encouraged simply because the extra precautions are never a bad thing). Especially if a "closed loop" system of drawing blood is in place?

I know you can't say for certain, but I'm wondering if you could help me understand in generalities:

a) We use Quest Labs - I'm assuming they would naturally use a "closed loop" system in terms of drawing blood? I'm not sure sure what "closed loop" means (still learning), but gather that this is always best practice, so imagine major labs like Quest or LabCorp would use this methodology?

b) In your opinion, is the risk of contamination extremely small in a "closed loop system"?

c) If we requested VEGF Plasma to be drawn first, do you know if there are phlebotomy practice measures in place to prevent contamination? In other words, since our phlebotomist didn't "bat an eye" by the request (and it's been three lab draws over the past 1.5 years), does that mean it's likely that the phlebotomist was aware of the "order of draw", was able to draw VEGF Plasma first per request, and then naturally took measures to avoid contamination because such precautionary systems are in place?

I know nobody here is psychic (smiles!), and you cannot say for certain whether contamination took place. I guess I'm just looking for your general comments here, for my own peace of mind and thought processing.

Thank you very much in advance!

[aroelisland]

Thanks all. Yeah, by "contamination" I meant the risk of an additive from one tube (say the EDTA from Lavendar Top) impacting the blood from sample taken next if not drawn per proper "Order of Draw."

Thanks!

[LovingLife123]

I always thought it had to do with the additives as well, as some have Heparin and others don't. Therefore, a closed loop system shouldn't come into play.

I don't know anything about the test that is ordered. But I don't know that I'd manually be writing anything on lab forms. I understand your doctor gives these forms to you, but that writing could be interpreted as his orders and writing.

If this doctor has a specific way he wants these labs drawn, this should be specifically spelled out in an order.

I think you are well meaning, but going about this completely wrong, as is the doctor. I would make it clear to the phlebotomist that you are manually writing this because the doctor told you this. They can then determine if further clarification from the doctor is needed, as the lavender tube is not first on the order of draw.

But again, we have no idea what labs are being drawn. But I'm guessing green tubes are getting drawn for electrolytes. Green before lavender.

[DowntheRiver]

This is just an example as to why there is an order of the draw:

"Any tube containing an alternate anticoagulant should be collected after the blue-top tube. Gel-barrier tubes and serum tubes with clot initiators should also be collected after the citrate tubes."

Prothrombin Time (PT) and Partial Thromboplastin Time (PTT)

[canoehead, BSN, RN]

By the way, this article is consistent with other research I've found on this... the idea that "Order of Draw" is great to continue, but not that important. I think the take-away is - why not practice order of draw, just to be extra cautious, but that in actual settings - the risk of contamination doesn't play out in lab settings? Again - would love your insights on this - I think I'm just hoping that, in the case of my family member, we haven't caused any issues in remaining labs by requesting VEGF Plasma first... :) (PDF) The order of draw: Myth or science?

The recommended order of draw is a blue top first, and it has to be full to run it. BUT I can get enough blood to run a CBC and a bunch of chemistries, including a VBG, on the blood a blue top takes. Those are much more emergent and essential labs for immediate treatment in most patients. If I can only get a tiny vein, or the patient is thrashing, I'll fill the tubes I wan or need the most first. That's when it makes sense to draw in order of need, not in the manufacturer's recommended order.

Where I've worked, the anticoagulant in the chemistry tubes is a solid on the bottom of the tube, so having it contaminant a needle at the top of the tube is very unlikely.