Removing serum from cells

[Antrita]

A part-time CLS asked me about a policy at another hospital where she works. All the serum must be removed from the clot within 2 hours from when it was drawn. If this is not done the patient has to be redrawn. This makes her very unconfortable, as she does not want to use serum that someone else has removed and labeled. I agree with her, we only remove the amount of serum/plasma that we need so the next person adding units is able to take from the original specimen. I know the Technical Manual does't say to remove all the serum. Wasn't there something about doing this a long time ago?

Antrita

[Lcsmrz]

Serum becomes anti-complementary when stored on cells; it is traditional to remove serum from cells to preserve adequate complement levels. I use EDTA plasma, so this issue is obviously moot.

Also, serum/plasma that remains on the cells may become "absorbed serum/plasma" if the patient was recently transfused.

I think the chances of mislabeling the pour-off tube far exceeds the possibility of missing a weak allo-antibody. I ask my techs not to separate patient samples.

[Antrita]

I doublechecked with the CLS. She said they don't draw serum for Blood Bank tests, only the pink EDTA tubes.

She is very unconfortable adding units to anyone because she is forced to use the pour-off tube. She is hoping that with response to this question here she will be able to get them to change their ways.

[clmergen]

We don't separate our pink top tubes at all. Anytime you can reduce the number of points for error the better.

[AMcCord]

We use EDTA and do not pour off. Too risky with the possiblity of mislabeling the tube.

[tbostock]

We use pink EDTA, do not separate. I agree with all about the potential for error.

[Mary**]

So do you recentrifuge if you have to reuse the specimen? Do you worry about autoabsorbption?

[Lcsmrz]

If the patient has not been transfused recently, autoabsorbtion in the refrigerator would be a good thing, reducing the titer of a cold autoantibody that I don't want to detect in the first place.

We recentrifuge previoius samples to remove particulates that may form durng storage and to make sure the sample is still platelet-poor.

[n.peters]

I would like to switch from using serum to plasma. Did anybody do some kind of validation when switching or has it just become acceptable practice to use plasma.

[ANORRIS]

What about storing the sample with a a serum separator in the tube?

[L106]

I would like to switch from using serum to plasma. Did anybody do some kind of validation when switching or has it just become acceptable practice to use plasma.

We did validation testing when we switched from serum from a red-top vacutainer to the pink-top EDTA plastic vacutainers. We had both tubes collected when the patients were drawn for Blood Bank testing and performed parallel testing. We did this long enough to ensure that a variety of antibodies were included in the study (as well as many samples without any problems.) (Exactly how many samples you need to test and what level of deviation between srum vs plasma is acceptable is up to your own decision.)

One other thing: Make sure that whatever type of vacutainer tube you are using for collection of your Blood Bank specimens is approved by the FDA for Blood Bank use.

Edited August 26, 2009 by L106

[Antrita]

We did a parallel study when we first started using gel, as a training tool. We did 100 patients and did not see any difference other than some fibrin on some of the serum specimens.

Antrita

[galvania]

What about storing the sample with a a serum separator in the tube?

As far as I know, these tubes have NEVER been validated anywhere for use in blood grouping/antibody screening. In some countries they are specifically forbidden.

[TimOz]

Anna is correct.

So called Gel tubes or SST (serum Seperation tubes) should not be used for immunohaematology testing.

The first reason is that it makes it very difficult to get at the red cells and the usable lifespan of the cells is shortened.

The second reason is that the gel can contaminate the cells and cause fale positive results.

To quote BD from their collection tube use guide "SST - For serum determinations in chemistry. May be used for routine blood donor screening and diagnostic testing of serum for infectious disease." That mean no IH testing.

There are very few papers on this subject but ther is a mention in this one from Chulalongkorn University in Bangkok: http://medinfo.psu.ac.th/smj2/web204/pdf204/Serum.pdf

[Malcolm Needs ☆]

I would like to switch from using serum to plasma. Did anybody do some kind of validation when switching or has it just become acceptable practice to use plasma.

There was a huge amount of validation performed before the switch from serum to plasma, particularly in the 1990-2000, although, needless to say, I can't put my hands on any of the work just at this moment.

Although it is now a little "elderly", it could be worth your while reading pages 132-133 and page 1182 of the tome by Peter Issitt and Dave Anstee, Applied Blood Group Serology, 4th edition.

That having been said, given that automation of antibody screening and (simple) antibody investigation, and positive sample identification for blood grouping relies on EDTA anti-coagulated blood, and the fact that there has been no evidence of mass transfusion reactions since its introduction, this, in itself, can be quoted as reliable validation of the use of plasma.

[John C. Staley]

Malcolm, you can add this to the list of things we agree on.

EDTA has been used for so long with no documented problems that switching from Serum to EDTA should be as simple as getting you phlebotomists trained to draw a different tube. Any more than that would be a waste of time and effort!!

[n.peters]

Thanks for the replies on switching.

[Malcolm Needs ☆]

Malcolm, you can add this to the list of things we agree on.

EDTA has been used for so long with no documented problems that switching from Serum to EDTA should be as simple as getting you phlebotomists trained to draw a different tube. Any more than that would be a waste of time and effort!!

Hi John,

I'm getting worried about this. Agreement between us is getting a bit too regular!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

:eek:

[djtito]

We remove our plasma and when stored they are rubberbanded together to make sure they stay together in storage. Fear of mislabelling should be at a minimum, mislabelling can happen all the way from the time the tube is being drawn, or even misidentification of the patient itself. But in the interest of complement, separation is the key.

[monnie48]

At our facility we use EDTA plasma. We do not separate the tubes, except for the case where the Type and Screen is done up to 3 weeks before patients surgery. We then separate and freeze plasma in case we need to add on a crossmatch.

[Eagle Eye]

we do not separate plasma. Keep same tube for 10 days.

[Judy hedglin]

We use the gel system and plasma is recommended. We only remove the plasma if the patient has a low crit to access the RBC for the red cell dilution in order not to contaminate the pipette. Then we immediately replace the plasma back into the original tube.

[Malcolm Needs ☆]

We use the gel system and plasma is recommended. We only remove the plasma if the patient has a low crit to access the RBC for the red cell dilution in order not to contaminate the pipette. Then we immediately replace the plasma back into the original tube.

Hi Judy,

I may well be being a bit obtuse here (it wouldn't be the first time) but isn't the whole idea of keeping the plasma on the sample so that there is no chance that the samples can be mixed up. Therefore, from a quality point of view, would it not be better to pipette out a sample of the red cells from the bottom of the tube, through the plasma, rather than to take the plasma off, then take out some of the red cells and then replace the plasma?

I see totally that, if you are handling one sample at a time, there is very little chance of a mix-up (and, indeed, because of the nature of the work in my own Laboratory, all samples are separated - strictly one at a time), but I just wonder if pipetting off a sample of packed red cells through the plasma would be "safer" from the quality point of view????

I don't know; I am just asking for your own opinion.

:confused::confused:

[Judy hedglin]

Hey Malcolm-

Our work volume is small--usually one sample at a time. We only remove the plasma if the crit is really low and immediately replace it. If it is a type and match-of course, respin.

[carolyn swickard]

What about storing the sample with a a serum separator in the tube?

There is a kind of plastic separator that can be added to tubes after the draw and before the spin down that is nothing like the SST gel. It might be usable (I think it is inert), but you would have to get your red cells out first before the separator was added and spun down.