Specimen for Fetal Screen

[Brenda K Hutson]

I just received a phone call from the Transfusion Service Supervisor at a local Hospital. She stated that she was getting flack from her Medical Staff for requesting that the specimen drawn for a Fetal Screen, be drawn 1 hour post partum. I told her I had never done that anywhere I worked but that I would look into it.

In thinking more about it, it occurred to me that we may not even have the Cord Blood and/or Cord Blood Orders within 1 hour post partum! We also do not consider Cord Blood Testing to be our top priority. That being said, we do of course perform the testing prior to the patient being discharged to assess any possible need for additional Rhogam.

This Supervisor stated that she had used a references that stated that it should not be drawn less than 1 hour post partum, but should then be drawn ASAP.

So, just wondering what the rest of you do? Any references to back your positions would also be appreciated.

Thanks,

Brenda Hutson, CLS(ASCP)SBB:)

[Malcolm Needs ☆]

I know that, when I was working in the hospital environment, the cord samples were taken at birth (as would be expected), but those taken on a Friday night were, on occasion, not tested until Monday morning and, apart from it being a bit close to 72 hours, nobody ever seemed to moan.

That having been said, I don't recall ever having seen any protocols.

:confused::confused:

[Brenda K Hutson]

We test our Cord Blood specimens daily on the Day and PM shifts. But even then, they are not top priority; they are done on any given shift, as soon as we can get them done. What I have mostly seen is that Hospitals want to wait until the following morning when the patient is having more blood work done, rather than sticking them twice (unless of course they have more bloodwork prior to that, or, will be discharged too close to the draw time).

So, I am not sure if the rationale for drawing them 1 hr post partum (by those who suggest that), has to do with having sufficient time to complete the Fetal Screen (and KB if necessary), plus give the Rhogam before the patient is discharged, OR, the test results would be expected to change the further one goes from delivery; if the latter, I have to admit I do not know how it might change.

Anyway, thanks; I can always depend on you to respond! I need to get back on and start giving input also but we have had one huge project after another at work and I just haven't had the time.

Brenda Hutson, CLS(ASCP)SBB

[L106]

I wonder if the other hospital is concerned that the number of circulating fetal red cells might diminish over time (ie: in the situation such as an O Neg mother with an A Pos baby; the mother's Anti-A +/or Anti-A,B may actually lyse the A Pos fetal cells.) Do you think this may be their concern?

[Brenda K Hutson]

I wonder if the other hospital is concerned that the number of circulating fetal red cells might diminish over time (ie: in the situation such as an O Neg mother with an A Pos baby; the mother's Anti-A +/or Anti-A,B may actually lyse the A Pos fetal cells.) Do you think this may be their concern?

Well, I guess that could be applicable in those situations where there is an ABO incompatibility, but obviously not for all; but perhaps rather than having to select your draw time "case by case," they might just want to make that general rule??

I guess I am just "guessing" unless someone who has that Policy responds with a reason...

Thanks,

Brenda Hutson, CLS(ASCP)SBB

[PaulSunV]

The Reference I thought of initially was from the AABB Technical Manual 15th Edition page 548 under Postpartum Evaluation. “A sample of the mother’s blood should be drawn, preferably within 1 hour after delivery, and evaluated for FMH of a quantity greater than that for which 300 µg RhiG is immunosuppressive.” But you are both right I don't know of any hospital that I have worked that the cord blood sample arrives in the lab within one hour after delivery and the testing often isn't a priority.

[Brenda K Hutson]

The Reference I thought of initially was from the AABB Technical Manual 15th Edition page 548 under Postpartum Evaluation. “A sample of the mother’s blood should be drawn, preferably within 1 hour after delivery, and evaluated for FMH of a quantity greater than that for which 300 µg RhiG is immunosuppressive.” But you are both right I don't know of any hospital that I have worked that the cord blood sample arrives in the lab within one hour after delivery and the testing often isn't a priority.

Yes, this Supervisor did say that it was in a previous Edition of the Technical Manual, but I do not find it in the current Edition. She also seemed to have a document that stated this was coming from John Judd??

I am just surprised to have worked in 6 different Institutions in my career, including 3 large well known Medical Centers and yet I have never heard of this???

If there is validitiy to it, I would also like to know.

Thanks,

Brenda Hutson, CLS(ASCP)SBB

[SusanM]

Our cords are tested on the day shift, so they are done the day after delivery if it's after noon and the specimen from mom is then collected later that day or the next AM with other labs (depending on how big a hurry she is to leave or how early we get them done). I can't imagine the screams (from both techs and the floors) if we attempted to type baby and get mom drawn as soon as 1 hour after birth!

[Malcolm Needs ☆]

I am going to be extremely controversial here, and will probably end up being universally hated by all BBT Members, but I think that an awful lot of the posts on this thread are missing the point and are forgetting basic immunology...there I've said it, so I am now probably in deep trouble!

The thing is that, as far as I can remember, the blood has to be taken from the mother after a certain time, but before an hour, because the red cells shed from the foetus/baby are, initially, sequestered into the maternal spleen (as is often found with "normal" transfusions) and then "released" back out into the maternal peripheral circulation. Hence, if the sample is taken too early, a falsely low number of the baby's red cells will be seen. On the other hand, after an hour, the maternal reticuloendothelium system (RES) will start to remove any D+ red cells that are sensitised by either the mother's own anti-D (or, indeed, anti-A and/or anti- and, once again, a falsely low count will be obtaained for the number of baby's red cells present. Therefore, there is a time, somewhere between half and hour and an hour, when the maximum number of baby's red cells will be in the maternal peripheral circulation.

Once the sample has been taken, however, apart from the normal degredation of cells that happens in all samples, the mix of maternal and baby red cells will not change over a long period of time (assumming that the samples are stored correctly).

This is because the antibodies themselves (the anti-D immunoglobulin that may already have been given during the pregnancy, or maternal anti-A and/or anti- will not destroy any of the baby's red cells. Antibodies themselves cannot destroy cells. The sensitised red cells in the maternal circulation will be destroyed (because they are sensitised) by the maternal RES (and, of course, there is no maternal RES in an EDTA bottle) or, in the case of, sometimes, ABO antibodies, by the maternal complement system. Even though the EDTA bottle will contain maternal plasma (and so maternal complement), the EDTA chelates Ca++, Mn++ and Mg++, all of which are required by the complement cascade, and so the cells in the bottle will not be destroyed by complement.

Therefore, once a "good" smple is taken, the various counts will not change for some time afterwards, and so when the actual estimation of the amount of baby's red cells present is performed is largely irrelevent (as long as the result is obtained in time to llow the correct dose of anti-D imunoglobulin to be given in a timely manner).

SORRY!

:redface::redface:

[John C. Staley]

Malcolm, I agree with every word. It's hard to argue with the science of it all.

The single biggest problem is that the collection of said samples is completely out of our hands. We are at the mercy of doctors and nurses who are clueless as to the mechanics involved that you just described. It is simply not a priority in their world. It was not unusual for us to not even be informed that a baby had been delivered until hours later when the cord blood sample finally made it to us (usually not labeled).

If anyone one can come up with a solution short of having a blood bank employee permanently stationed in L&D they will have done us a great service.

:bonk:

[L106]

And I agree with everything that John and Malcolm said. Nurses in the nursery frequently say that they are just "so busy" that the cord blood specimen often doesn't get sent down to Blood Bank for six to twelve hours after it is collected. (AND we have a pneumatic tube system!! AND they frequently are not labeled correctly, as John mentioned.)

Nevertheless, since the Fetal Maternal Hemorrhage Screening Test seems to be so sensitive (actually, overly-sensitive) I am very comfortable that even with our laxed collection processes we are not missing large fetal bleeds that would require additional doses of Rh-Immune Globulin.

[John C. Staley]

I forgot to mention, keep in mind that if what we have been doing was not working we would be seeing a much higher rate of anti-D amoung our young childbearing women. It's not a perfect world but we do the best we can. Just try not to get too hung up with the things we have no control over.

:fingerscr

[L106]

I forgot to mention, keep in mind that if what we have been doing was not working we would be seeing a much higher rate of anti-D amoung our young childbearing women.

:fingerscr

My thoughts exactly.

[MAGNUM]

Upon completion of the cord blood workups, if the patient needs the rhogam workup to be done, they are drawn with the next blood draw, usually the next morning with their HH. We went thru this recently with our L&D nurse manager and she could not find nor show me documentation that they must be drawn within the first hour post delivery.

Ultimately no proof, no time change.

[Mabel Adams]

It used to be in the Fetal screen package insert to draw ASAP after one hour after delivery. I thought it said due to the removal of ABO incompatible fetal cells, but I might be wrong. I always thought that was sort of pointless considering the history of ABO incompatible Rh pos babies being less apt to sensitize Rh neg moms. I also know that next to no lab is able to meet this timeline.

As for the spleen sequestering the fetal red cells, why would it see them as any different from transfused cells if they were ABO compatible and not coated with Ab? Is it the Hgb F? Or do all transfused cells visit the spleen for a bit before getting out about the circulation? I wonder who managed to do such timely and interesting research of newly delivered women's spleens?

(BTW, Malcolm, you spell things funny.)

[Malcolm Needs ☆]

(BTW, Malcolm, you spell things funny.)

It's UK English (with a bit of Greek and Latin derivation thrown in)!

If it's any consolation, I am often accussed of thinking in a weird way too!!!!!!!

:D:D:D

[jcdayaz]

I just received a phone call from the Transfusion Service Supervisor at a local Hospital. She stated that she was getting flack from her Medical Staff for requesting that the specimen drawn for a Fetal Screen, be drawn 1 hour post partum. I told her I had never done that anywhere I worked but that I would look into it.

In thinking more about it, it occurred to me that we may not even have the Cord Blood and/or Cord Blood Orders within 1 hour post partum! We also do not consider Cord Blood Testing to be our top priority. That being said, we do of course perform the testing prior to the patient being discharged to assess any possible need for additional Rhogam.

This Supervisor stated that she had used a references that stated that it should not be drawn less than 1 hour post partum, but should then be drawn ASAP.

So, just wondering what the rest of you do? Any references to back your positions would also be appreciated.

Thanks,

Brenda Hutson, CLS(ASCP)SBB:)

We require our Rh evaluations to be collected at the 1 hour mark post delivery. We don't begin running a Fetal Screen workup until a cord blood sample has been received and results obtained but we have the specimen at the 1 hour mark. As a matter of fact, we (in normal circumstances) batch our fetal screen specimens and process them only once a day in the morning.

Not sure about specific references, but I have always been taught that the ideal time to detect significant fetal-maternal bleed is 1 hour post delivery.

Obviously this does not apply to antenatal trauma/problem situations. Any woman >13 weeks gestation gets a fetal screen in a trauma/problem situation. We still give Rhogam if the woman is <13 weeks gestation, but without doing a fetal screen. Once again, not sure the specific reference to give you, I am at home right now. Perhaps I will have the opportunity when I get to work today to obtain a reference for you.

[Malcolm Needs ☆]

As for the spleen sequestering the fetal red cells, why would it see them as any different from transfused cells if they were ABO compatible and not coated with Ab? Is it the Hgb F? Or do all transfused cells visit the spleen for a bit before getting out about the circulation? I wonder who managed to do such timely and interesting research of newly delivered women's spleens?

Hi Mabel,

Yes, transfused red cells do get sequestered in the spleen, or, should I say, at least small volume red cell transfusions get sequestered to the spleen for a time (unless they are destroyed by intravascular haemolysis). This was shown with radio-isotope-labelled red cells, in the days when they used to inject small volumes of incompatible red cells to see how long they survived in the circulation (and thus boosted the antibody titre!). The red cells disappeared into the spleen for a while before coming back out into the circulation.

Obviously, this does not happen in cases of large volume transfusions.

I have never read that such research was done on newly delivered mums, get I have a very strong suspicion that the situation was extrapolated from these isotope experiments. Whether or not it actually holds any water, I know not.

:confused::):confused:

[Steven Jeff]

(BTW, Malcolm, you spell things funny.)

[TimOz]

Steven, I think Mabel is referring to the diphthong thing - Haem and Foetal etc. instead of the US spelling Hematology and Fetal. I assume from you location that you know the "English" English as opposed to the "collonial" version.

Back on topic. Can we change the name of this test????

I think we are actually doing 2 things here: 1. Doing an FMH screen to see if there are any detectable Foetal cells in teh maternal circularion and 2. An FMH Quantitation do determine the dose of therapeutic Anti-D IVIg to infuse. It seems that sometimes these things get confused as the Kleihauer used to be used for both (in my opinion is is good for purpose 1 and hopeless for purpoose 2.

FYI, as of a few years ago all pregnant RhD neg pregnant women in Australia receive 3 doses of Anti-D during the pregnancy as a matter of course. FMH screening is now used to determine if there has been a massive bleed during delivery that would indicate a higher dose is required. We still have a small nhumber of alloimmunisations but the rate is very low now.

[Malcolm Needs ☆]

Steven, I think Mabel is referring to the diphthong thing - Haem and Foetal etc. instead of the US spelling Hematology and Fetal. I assume from you location that you know the "English" English as opposed to the "collonial" version.

QUOTE]

I think that you are correct Tim.

Actually, I prefer it when the letters are actually joined in the diphthong, but you can't do that on here.

Maybe it's because I still tend to write essays and things like that on stone tablets with a hammer and chisel!!!!!!!!!!

:D:eek::redface::tongue::tongue:

[jcdayaz]

The thing is that, as far as I can remember, the blood has to be taken from the mother after a certain time, but before an hour, because the red cells shed from the foetus/baby are, initially, sequestered into the maternal spleen (as is often found with "normal" transfusions) and then "released" back out into the maternal peripheral circulation. Hence, if the sample is taken too early, a falsely low number of the baby's red cells will be seen. On the other hand, after an hour, the maternal reticuloendothelium system (RES) will start to remove any D+ red cells that are sensitised by either the mother's own anti-D (or, indeed, anti-A and/or anti- and, once again, a falsely low count will be obtaained for the number of baby's red cells present. Therefore, there is a time, somewhere between half and hour and an hour, when the maximum number of baby's red cells will be in the maternal peripheral circulation.

Once the sample has been taken, however, apart from the normal degredation of cells that happens in all samples, the mix of maternal and baby red cells will not change over a long period of time (assumming that the samples are stored correctly).

Therefore, once a "good" smple is taken, the various counts will not change for some time afterwards, and so when the actual estimation of the amount of baby's red cells present is performed is largely irrelevent (as long as the result is obtained in time to llow the correct dose of anti-D imunoglobulin to be given in a timely manner).

SORRY!

:redface::redface:

Sorry Malcolm, still no hate here for you!!!

What you stated is precisely the premise behind our policy to collect Fetal Screen specimens 1 hour post delivery. We will centrifuge and refrigerate the sample for testing to be done the next morning (in most cases).

[jcdayaz]

the diphthong thing

:D:eek::redface::tongue::tongue:

I will confess my ignorance on the "dipthong thing" topic. I have no idea what you guys are referring to. Care to enlighten me? Thanks a million.

[Malcolm Needs ☆]

I will confess my ignorance on the "dipthong thing" topic. I have no idea what you guys are referring to. Care to enlighten me? Thanks a million.

A diphthong is when two letters are pronounced as one (for want of a better way of putting it), so that US English will spell the word as "fetus", whilst UK English (or, at least, old fashioned fuddy-duddies like me) will spell the word as "foetus" - the "oe" bit being the diphthong.

Originally, the o and e ran into each other in the spelling, so that the left half of the "o" showed, but the right half of it sort of "slid" under the left half of the "e".

You can see what I mean much easier in the attachment.

:D:D:D

Diphthong.doc

[jcdayaz]

A diphthong is when two letters are pronounced as one (for want of a better way of putting it), so that US English will spell the word as "fetus", whilst UK English (or, at least, old fashioned fuddy-duddies like me) will spell the word as "foetus" - the "oe" bit being the diphthong.

Originally, the o and e ran into each other in the spelling, so that the left half of the "o" showed, but the right half of it sort of "slid" under the left half of the "e".

You can see what I mean much easier in the attachment.

:D:D:D

That's interesting. Thanks for the attachment.

One question for the computer illiterate among us (myself included), how did you get the letters to "slide" in your second version of each word?

Thanks again!