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Liz0316

cord blood

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I was always taught that cord blood specimens shouldn't be used for the pretransfusion type and screen on a neonate.

 

Is anyone using the cord specimen for the initial type and screen? If not why not?

 

At our hosptial we don't, normally we use a bullet and the mother's plasma for A/S, but now I have a neonatologist who wants to change that.

Thoughts?

Liz

 

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I think there are two reasons we don't use cord specimen

1.the Wharton jelly in it will cause rouleux agglutination of cells

2.the antibodies came from the maternal circulation will be concentrated in the cord blood, the concentration is higher than in the maternal blood and neonate's blood circulation, will cause false positive.

Edited by shily

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Also did not use cord blood results for transfusion purposes.  You can never be sure what is labeled as cord blood is actually cord blood and not maternal sample.  Blood type differences may help but still better to have a standard practice. On the other hand, if you're transfusing only group O RBCs and AB plasma probably not as significant until sometime after 4 months when the patient is typed again and a different result is obtained. 

 

Along the same lines, we also required a neonatal/heelstick sample in cases where the mother was Rh-neg and the cord blood sample tested the same ABO/Rh as mother as confirmation that RhIgG was not required.  Did not see discrepancies that often however they did occur and one missed RhIgG prophylaxis resulting in immunization is enough to justify practice. 

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We DO use cord blood for pretransfusion testing but prefer a direct sample from the baby ... which is not what they want to do when a child actually needs a transfusion.

All Cord Blood is specifically labeled according to our current pretransfusion sample criteria.

It is a special blue top, non-vacutainer tube ... no confusion possible with maternal sample.

We use gel testing.

In gel, you can easily see dual populations ... as opposed to tube testing where 'mixed field' is difficult to detect.  N.b. We were all taught many years ago that newborn ABO Typing is weaker than in adults.  There's an Editor's note in an old Transfusion journal that describes that these 'weaker ABO Types' were most likely dual population (mom and baby).

Wharton's jelly is not a problem. (I've actually heard that's an 'old wive's tale' from some people.)

If there are antibodies in the Cord Sample from the mother, well, we actually DO want to see them.

 

Note:  We issue O negative RBCs (with other special requirements), so even if the Blood Type were in question, it is a mute/moot point for the transfusion.

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In gel, you can easily see dual populations ... as opposed to tube testing where 'mixed field' is difficult to detect.  N.b. We were all taught many years ago that newborn ABO Typing is weaker than in adults.  There's an Editor's note in an old Transfusion journal that describes that these 'weaker ABO Types' were most likely dual population (mom and baby).

 

I've often seen this, but it is now known that, in almost all cases, it is not due to a mixture of maternal and baby blood.

 

It is now known that it is due to the transferase enzymes (3 -alpha-N-acetylgalactosaminyltransferase for A and 3-alpha-galactosyltransferase for B, and the direct gene products of the ABO locus) in the baby not working at their kinetic maximum at birth (particularly in a preterm neonate), and so the H antigen is not yet converted to either A or B.

 

If this were not so, then we would see a lot of "negative" cells in a Kleihauer performed upon the cord blood (I know, I know, the Kleihauer is done on the maternal blood, not the cord blood - but you would see a lot of "negative" cells were it to be performed on the cord blood).

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Malcolm,

I follow what you are explaining up to the last sentence. We always use a random Cord blood specimen as a positive control for the Kleihauer stain because

this stain is specific for Fetal Hgb and it is a rare occasion when this positive control comes up negative; and if it does it is usually do to human error.

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What I was saying is that, if a "mixed-field" ABO reaction was regularly due to there being a mixture of maternal (presumably group O) blood and baby (presumably A, B or AB) blood, then if a Kleihauer test were to be performed on these samples, you would see a substantial number of ghost (maternal) red cells in the film, in which the HbA has been destroyed - and you don't.

 

This proves that, in most cases where a "mixed-field" ABO reaction is seen with cord blood, all (or the vast majority) of the red cells are from the baby, with HbF intact, and staining with the eosin.

 

I've just re-read this, and I think I could have written this more clearly, but the problem is that "I know what I mean"!!!!!!!!!!!!

 

:confuse:  :confuse:  :confuse:  :confuse:  :confuse:

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We DO use cord blood for pretransfusion testing but prefer a direct sample from the baby ... which is not what they want to do when a child actually needs a transfusion.

All Cord Blood is specifically labeled according to our current pretransfusion sample criteria.

It is a special blue top, non-vacutainer tube ... no confusion possible with maternal sample.

In my experiences, the problems encountered with maternal blood in tube instead of cord were with the collection process, not the labeling process. The samples were clearly labeled as cord samples, however, however OB did the collection, it contained maternal blood.

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Our cord blood specimens are labeled with the mother's wristband label (MobiLab) and a Cord Blood sticker, so we don't have the identifiers we would need.  We also did a study and found that the majority of cord blood specimens are not labeled right at the time they are collected.  For those reasons, we do not use them for type & screen or crossmatch purposes.

 

NICU nurses have recently been collecting specimens from the baby side of the placenta for genetic studies and crossmatching.  These specimens are labeled with a MobiLab lab made from the baby's ID band at the time of specimen collection.  As per the literature, these specimens are okay to use for Blood Bank purposes.  They only collect these on single births, no twins or triplets, etc.

 

Our neonatalogists understand what we require for crossmatching.  If they need blood products prior to Blood Bank receiving a specimen, they request Uncrossmatched blood.

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Also did not use cord blood results for transfusion purposes.  You can never be sure what is labeled as cord blood is actually cord blood and not maternal sample.  Blood type differences may help but still better to have a standard practice. On the other hand, if you're transfusing only group O RBCs and AB plasma probably not as significant until sometime after 4 months when the patient is typed again and a different result is obtained. 

 

Along the same lines, we also required a neonatal/heelstick sample in cases where the mother was Rh-neg and the cord blood sample tested the same ABO/Rh as mother as confirmation that RhIgG was not required.  Did not see discrepancies that often however they did occur and one missed RhIgG prophylaxis resulting in immunization is enough to justify practice. 

Do most transfusion services follow the practice in the second paragraph? I'm afraid I must admit, I haven't thought of this before.

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I had never thought of this either - tough sell to get more heelstick specimens though.  And it has been a long time since I have seen Wharton's jelly in a specimen - but we did see it occasionally (different collection techniques, I think) and still teach the newbies to watch out for it.  We do not use cord blood for crossmatching at all - labeling is wrong and we use a unique armband for Blood Bank.  Most of the time, it is quite a while after birth too (usually days) before they start asking for blood.  Pretty rare we get a request early on except for the occasional "Exchange Transfusion" scare that almost always gets cancelled with the aggressive hyperbilirubin lowering treatments they manage now. 

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I know we want to get the high concentration of antibodies, it is the reason we use enhancement in our testing. My meaning is there is part of antibodies which will not be the culprit of HDFN, or weaker  in the newborn's blood circulation will not cause severe HDFN. Use cord bloods will cause confusion.

Because the IgG antibodies are transported by the placenta, will be concentrated in the cord bloods.

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Wharton's jelly may be more of a problem if the cord is cut and "milked" to collect the blood rather than using a needle into the umbilical blood vessel, or so I've heard.

 

I knew of someone that did a variant of the old APT test on cord samples to be sure that they were fetal blood (fetal Hgb).  Sodium hydroxide was used as I recall. It was at a hospital in London, Ontario, Canada.

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We see a fair number of nasty cord bloods with Wharton's jelly. It is all about the technique they use to collect the sample. If the outside of the tube is disgusting with lots of blood, I know it was collected by the cut and drip method. (Can't seem to get them to clean up their mess - they don't see the point.) We also don't use it for crossmatching, though our nursing policy for transfusing babies says we do - apparently they don't see the need to ask US how we do the test.

 

In a pinch we will use the mother's plasma for the crossmatch if using type O red cells for transfusion and if transfusion occurs within a day or so of birth. The babies have armbands that link them with mother so we get positive ID with mom. Though we deliver lots of babies, we rarely transfuse them - they get shipped out if they are that sick.

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You can never be sure what is labeled as cord blood is actually cord blood and not maternal sample.  

 

Of course you can - you can either use 0.1M sodium hydroxide to determine if the haemoglobin is foetal or adult, or you can compare the MCV of the cord and maternal sample - 99.9% of the time the maternal sample will have a low MCV and the baby one high.

 

I've used both methods in different laboratories as a method to determine if the baby sample is really baby when both groups are the same and the mother is Rh neg.

 

We only issue O-neg to neonates so have no issue with cord samples (as long as they meet national labelling criteria). 

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wow, lots of really cool thoughts on this topic. I have decided to use the cord blood for the ABO/Rh and DAT on baby. Mother's type and screen and possible XM. We will only XM if the mother has an atypical antibody. Other than that we are using O neg pedi packs.

We are going to issue the units as emergency release - it's just easier in SQ

As for ABO confirmation (second specimen) we can usually use a sample from hematology or chemistry, but when I spoke with the neonatologist he said that any baby needing a transfusion has a line in and if we need, we can always get a few drops for ABO confirmation.

In the event that the mother is not available, a type and screen (and DAT) will be done on the baby from a fresh specimen.

I also checked with other hospitals in my state and this is what they are doing. So I have avoided using the cord for type and screen, have a back up and everyone is happy.... halleluiah !

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I was taught from Day 1 that a Cord Specimen should never be used for transfusion purposes; and that has been the Policy at the 6 Hospitals I have worked at.  I believe the reaasons to be:

  1. Possible contamination
  2. Risk of specimen not belonging to that baby.  I can atest to the fact that cord specimens are by far the most mislabeled specimens in a Hospital (I believe it to be due to the different workflow involved which increases this risk).  While there can be a variation on this theme, it may play out something like this.....Cord specimen is obtained by Physician who then hands off the "unlabeled" specimen to someone else to label; this someone else may or may not even be present in L&D at the time; they then place the mom's label on the specimen; then they hand it off to someone (perhaps in the Nursery) who will have the baby's label once the baby has been registered.  This leaves a lot of room for errors.

Brenda Hutson

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Sorry to resurrect an old thread but as my question has already been discussed in this thread I thought it worth continuing here.

I want to know if anyone has a technical explanation as to how a large amount of maternal contamination of a cord sample can occur?

In the UK in my experience at all labs I've worked its always been practice to perform APT (NAOH)  test on all cords that give the same blood group as the mother, I've always seen this as one of those tests you just do but seems a bit of a waste of time as its never positive.

Last night we had a cord sample giving group O Pos result but with weak reactions in the B and AB wells.

I advised the staff member to wash the cells and repeat, this then showed a strong mixed field, O and B. We requested repeat venous blood which was B Positive the mothers blood group is O Pos. 

APT test showed the first sample was not, or at least not all Neonatal blood. 

I've done a bit of a google search and although there are a lot of papers discussing contamination there isn't much that describes exactly how it occurs. I'm assured the samples are taken by double clamping then taking the blood with a syringe and needle. 

 

Thanks 

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I am not sure how contamination occurs either but it does.   I think more frequently, incorrect labeling (patient ID) occurs which may be the case in the first gel card.    On the other 2 cards, this looks like a case of the B antigen not fully expressed at birth and therefore giving weak (mixed field like) reactions.  The difference in strength with the last 2 could be that there was some incubation of cells and sera prior to spinning.    If you really want to do more work to determine if this is contamination, you could do some Rh phenotyping (just for fun)  but mom and baby would have to have different Rh phenotypes for this to work.   Rh is fully expressed at birth so there should be no mixed field.   I am sure there are other ways to investigate contamination and I am sure others will chime in.     What is APT (last pic)? 

Edited by R1R2

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2 hours ago, R1R2 said:

On the other 2 cards, this looks like a case of the B antigen not fully expressed at birth and therefore giving weak (mixed field like) reactions.  The difference in strength with the last 2 could be that there was some incubation of cells and sera prior to spinning.    If you really want to do more work to determine if this is contamination, you could do some Rh phenotyping (just for fun)  but mom and baby would have to have different Rh phenotypes for this to work.   Rh is fully expressed at birth so there should be no mixed field.   I am sure there are other ways to investigate contamination and I am sure others will chime in.     What is APT (last pic)? 

The first and second cassette are the same specimen, the only difference was the washing of the cells between the first and second runs. I don't have an explanation as to why washing the cells changed the reactions from 0.5+ to mixed field but it seems to have increased the strength of the group B cells.

There should be no incubation of cells and sera, it was performed on an analyser and they are immediate spin, even if slight delay in centrifuging the sera and cells should be separated until centrifugation.

The APT test is alkaline denaturation, identifies cord blood from adult blood. The first specimen definitely had adult blood in it.

Edited by srichar3

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I believe newborn and maternal red blood cells do not have exactly the same density. So, on 2 different sampling even from the same tube of packed cells, you may have diff. proportions of maternal vs newborn red blood cells. It is the same in case of transfusion, as transfused cells are heavier, depending on the way RBCs are sampled (bottom/middle/top of packed cells) you may have diff. results/pictures (DP, no DP...). 

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