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

Sour Lemon · Aug 16, 2018

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!

I have no idea what an NTC even is. And in the hospital jobs I've had, phlebotomists have been responsible for drawing labs- not nursing staff. Have you considered discussing this with lab staff or the physician who made the recommendation?

**canoehead, BSN, RN** · Aug 16, 2018

I drew labs when I started an IV line for about five years in another ER, and was completely ignorant to order of draw. Never had a lab come back with a bad result that wasn't confirmed bad with a second draw. So I think the order of tubes is something done without any real evidence. Maybe there's a 1:10000 chance of affecting the result, but it would likely make the result so outlandish that we'd redraw to recheck it.

aroelisland · Aug 16, 2018

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?

Home Health Columnist / Guide · Aug 16, 2018

Comments below based on my 10yrs home health experience with IV infusion company performing home lab draws.

VEGF = Vascular Endothelial Growth Factor, Assessment of tumor progression and prognosis ---this test is used for research purposes and not common lab test. Specimen drawn needs to be transferred to special tube for freezing ASAP after obtaining specimen.

11721: Vascular Endothelial Growth Factor | LabCorp

Order of labs drawn is established based on presence/absence of preservative use in blood collection tubes. Closed loop system is veinipuncture device (inserted in skin) with vacutainer attached to be able to insert and draw blood into multiple blood collection tubes rather than just using one syringe(old days). My crystal ball suspects doctor wants freshest specimen of blood rather than end of draw as blood can hemolyze/congeal at end of lab draw or have minimal amount in tube. There is minimal risk of contamination i.e infection with todays modern closed loop systems as long as skin is prepped prior to blood draws. Both Quest and LabCorp computer systems these days have lists of tests, type of lab tube to obtain specimen and any special requirements for lab draw order and special specimen handling/processing see web links below.

TUBE CHART AND ORDER OF DRAW

Blood Collection - Quest Diagnostics

Physician ordering test should specify on lab slip desires this test to be drawn FIRST to alert lab personnel as not a standard test techs are familiar with drawing.

Using same lab location and techs to draw labs can ensure continuity of labs being obtained and processed. Please address any concerns with physician and lab facility staff.

Best wishes for your family member getting treatment.

aroelisland · Aug 16, 2018

Thank you for your reply canoehead! :)

Really appreciate this - and hoping that's the case for my family member (i.e. a non-issue!). I think because we are following labs (about 40!) following a cancer diagnosis that is fortunately in remission, we are extra cautious... In fact, it was this caution and extra attention that led to us asking for VEGF Plasma first, a suggestion by our doctor to allow for consistency, since VEGF, by its nature, deals with vascular inflammation - so if it's the 14th tube of blood drawn, it can in theory show false increases just due to the puncture of skin for blood draw.

That preciseness on our parts works well, in theory! Until I learned that there's an "Order of Draw"! Ha! But I'm hoping our phlebotomist took all of this into consideration as well, especially because they're at a major lab and didn't bat an eye at the request.

Thanks again!

aroelisland · Aug 16, 2018

Thank you NRSKarenRN! I appreciate your reply as well...

Our doctor is out-of-state, but provides lab requisition forms for us electronically. And after he mentioned that VEGF Plasma (which you're right, is uncommon!) be drawn first, we manually wrote in on the lab requisition form, "Draw VEGF Plasma first" - which our phlebotomist at Quest did (and has continued to do for the last three rounds of labs - we always go to the same lab). In other words, he draws VEGF Plasma (lavender top) first, then proceeds to draw about 14 other tubes of blood, which I presume he does following the more traditional "Order of Draw". So that's led to the concern of a Lavender Top tube preceding many other tubes which should traditionally "go first".

So am I understanding you correctly here?

- That with a high quality and experienced lab like Quest, they would automatically be using a Closed Loop system (i.e. prepped skin, Vacutainers, etc.)...

- That because of this, risk of contamination of blood collected in tubes despite "Out of Order" Draw is extremely low, or non-existent.

I'm a Type A personality (occasionally to my detriment!) so over-analyze everything. Appreciate your time, and very encouraged by your response.

Thank you!!

aroelisland · Aug 16, 2018

Hi Sour Lemon, yes... I have reached out to the Lab / Phlebotomist, and have not gotten a response yet (massive lab, many hoops to jump through to get answers) - I imagine they will of course say that procedures were followed and "no risk of contamination". I imagine if they had concerns about the request for VEGF drawn first, they would have voiced that at the time...

That's why I'm asking here, just looking for your expertise / opinions.

Thank you!

Home Health Columnist / Guide · Aug 16, 2018

Hi...your understanding of my post is correct. Have a good day.

AnnieOaklyRN, BSN, RN, EMT-P · Aug 16, 2018

This is probably something that should further be discussed with the lab and physician, not with the internet. We are nurses and don't specialize in lab draws.

Annie

psu_213, BSN, RN · Aug 16, 2018

That with a high quality and experienced lab like Quest, they would automatically be using a Closed Loop system (i.e. prepped skin, Vacutainers, etc.)...
- That because of this, risk of contamination of blood collected in tubes despite "Out of Order" Draw is extremely low, or non-existent.

What do you mean by contamination? Contamination of blood cultures by skin bacteria are is prevented through proper skin prep, proper prep of the tops of the vials, used of a closed looped system, etc. Contamination of ABG/VBGs by air is prevented through use of the correct sampling container and expelling air from the collected sample. Correct order of draw can prevent contamination of the sample with an additive from another tube. For instance, some tubes contain heparin. Theoretically, some of that heparin could end up on the end of the needle that puncture each tube (sorry, don't know all the precise names for each part of the device). If the light blue (sodium citrate) tube is drawn next, I suppose some of that heparin could end up in that tube and throw off your PTT result. This is my guess, not a scientific fact, so someone is free to dispute it. OTOH, I'm not sure if that small amount of heparin transferred to the light blue tube would really make that much of a difference anyhow.

As for the closed loop system, never say never/always, but I have almost always have blood drawn via a closed loop system at Quest or at a hospital based lab.

What is NTC?

DowntheRiver · Aug 16, 2018

Order of the draw is more important with blood drawn from IV or VADS (port, PICC, etc.) versus peripheral venipuncture due to (as mentioned) possible contamination due to back flow. Very, very minute chance it can happen and not as much with modern vascular access devices. However, order of the draw is still stressed at my facility (top ten Oncology hospital).