Has anyone heard of using a DAT to screen for FMH? We have used the Rosette tests in the past. One of our students tells me of another facility that does a DAT. They examine the DAT under the microscope and if they see any agglutination at all, they send the specimen out for quantitation. I have some misgivings about this and am wondering what others think of this idea.

Has anyone heard of using a DAT to screen for FMH? We have used the Rosette tests in the past. One of our students tells me of another facility that does a DAT. They examine the DAT under the microscope and if they see any agglutination at all, they send the specimen out for quantitation. I have some misgivings about this and am wondering what others think of this idea.

LEFT FIELD IN THE EXTREME!!!!!!!!!!!

:eyepoppin:eyepoppin:eyepoppin:eyepoppin:eyepoppin

Decades ago we used the weak D (Du) as part of our testing for FMH, but that was in the early 1970's.

The Direct Coombs would only be useful if the mother had anti-D and the fetal cells were coated. The weak D test was determined to not be sensitive enough to detect the level of fetal-maternal bleed that could result in sensitization. The only methods that currently are able to detect that level of bleed are the fetal screen (rosette), the Kleihauer Betke, and the flow cytometry.

If I recall correctly, it used to be a part of either the AABB or the CAP checklist that a weak D test cannot be substituted for performing a fetal screen. I guess I'm showing my age:)

I'm with David, who ever brought this up has either been around the block a few times, like me or has found a very, very old reference book. I'm surprised the idea is still out there and I do mean OUT THERE.

Many years ago some sites used the Du test to screen for FMH. However, it was estimated that a fetal bleed of about 50ml rbc would be needed for the average tech to recognize this as a positive Du. That's why the method is no longer employed.

Don

We looked at maternal "Du" results microscopically until the first rosette test became available. That was many moons ago., but I guess I'm showing my age!

In about 1981 we were doing Kleihauers on all postnatal specimens for a few months until the first rosette kit came on the market. Before that the Du test was all we had, but never a DAT.

Can we use flow cytometer to determine it?

Can we use flow cytometer to determine it?

Yes, and that is the recommended method for quantitation of FMH in the UK.

I wish we all had access to flow cytometry for it. Somebody could get rich if they could get the blood cell counters in Hematology that use flow cytometry so that they could test for fetal Hgb.

Since the information was coming from a student, I would wonder if they misunderstood what they were told or saw. If that's not the case...YIKES!

Can we use flow cytometer to determine it?

Fetal f Hgb is the gold standard. Problem is availability.

Decades ago we used the weak D (Du) as part of our testing for FMH, but that was in the early 1970's.

I did this too....and to further date myself, I went to a seminar where the rosetting technique was first described........before there WAS a kit!

Nancy, I would love to hear where your student said this was still being done. I hope they misunderstood!

Hi-De-Hoo! Long time, no post, but yes, I did remember my password!

Anyway, a question as it relates to this thread: last night we had an emergency transfusion of a newborn, mother's blood type and baby's blood type was A-positive, with a negative DAT on the cord cells. We gave the baby O-neg, irradiated because there was no time to order from the Red Cross, the special packs they make up for neonate transfusions. The doctor wanted a Kleihauer Betke done on the mother, and I wanted to ask if it makes sense to everyone else to order that? I know it's usually done primarily on Rh negative moms to determine rhogam dosing, but where it's actually detecting fetal hemoglobin, would it work the same on an Rh positive mom as far as showing the extent of a feto-maternal bleed?

My Goodness! Welcome back LisaM. After such a long time, it is like making contact with the ghost of Landsteiner over the ether!

I, personally, think that it is a waste of time. They Hb and Hct of the baby's blood is a far better measure of how much of a foeto-maternal haemorrhage there has been, in terms of how much blood the baby may require to bring him/her back to (reasonable) health.

The Kleihauer (and, come to that, flow ctyometry) can give very strange results, if the FMH has been chronic, rather than acute. Just as an example, one of our hospitals had a flow the other day that showed 175mL of FMH. Now, if that had been an acute bleed, the baby would be empty! It must, therefore, have been a chronic bleed, which meant that the baby's own bone marrow (and quite possibly other ectopic haemopoietic tissue) would be compensating/would be "over active" trying to bring the baby's Hb and Hct up to scratch, and the actual Hb and Hct of the baby at birth may not be reflected by the Kleihauer or flow results at all.

I thought ether-sniffing was only glamorous in the 1800's when they didn't know it could kill you, Malcolm???? LOL

And thx for the reply--I thought it was a waste of time, doing the KB. The baby's H+H was something like 4 and 16--really bad, and they shipped it out to a hospital better equipped to deal with trauma like that, but we had to pump some blood into the baby before it was transferred. The mom is a drug addict and Hep-C positive, so I'm sure Social Services will step in, next. . . .

I suppose the Dr.'s logic was wanting to see if the baby bled into the mom or out onto the puddle pads. Not that it makes a whit of difference in treating either mom or baby. Couldn't very well have a brain hemorrhage and end up with counts like that--unless the head was the size of a pumpkin.

The doctor wanted a Kleihauer Betke done on the mother... .... but where it's actually detecting fetal hemoglobin, would it work the same on an Rh positive mom as far as showing the extent of a feto-maternal bleed?

We would only do it for a coroners case where the baby/foetus has died due to an unknown cause.

We do K-B on quite a few Rh pos moms - traumas and fetal demise being the main indications. K-B (and flow) detect fetal hemoglobin and has nothing to do with mom's Rh. The rosette screen is a different matter - it's dilute anti-D and should not be done on Rh pos moms as it will always be pos.

Under what conditions would you NOT perform the Rosette test and do a Kleihauer instead.....from what I've read there are the obvious times like either Mom or Baby are Weak D positive or mom has a positive DAT that is interferring.

What about if Mom was givien RHIg prior to the sample being drawn .... ??one might worry the antigen sites of any Rh;Pos are covered by the RHIg and won't be detected by the kit Anti-D??  If you agree with this scenario how long would you consider the RHIg to interfere?

As a lab serving a busy maternity unit we would routinely perform a Kleihauer test on all mothers, regardless of blood group, who suffered an IUD or gave birth to an unexpectedly anaemic child as the result was of great assistance to the Coroner or Paediatricians.

Although not peer reviewed, unofficial and entirely anecdotal we used to find that foetal cells which had been in the maternal circulation for any length of time would appear crenated in the Kleihauer and seeing many such cells was strongly suggestive that the bleed had been chronic rather than acute.

I found it very annoying that so much useful information could be gained from this test as I always loathed the Kleihauer with a vengeance.

We do K-B on quite a few Rh pos moms - traumas and fetal demise being the main indications. K-B (and flow) detect fetal hemoglobin and has nothing to do with mom's Rh. The rosette screen is a different matter - it's dilute anti-D and should not be done on Rh pos moms as it will always be pos.

Same at my place Kate.