Just had a Nurse Practitioner request an Rh Type on a Fetus using mom's specimen.  I was not aware of any such test; but she said it was new and that it did exist.    Looked on Intranet and found FETAL RHD GENOTYPING by Sensigene.

Does anyone perform this?  What is the reliability?  Doesn't seem either of our reference labs even perform it....

Thanks,

Brenda Hutson, CLS(ASCP)SBB

Hi Brenda,

 

Yep, we've been doing it for a few years now this side of the pond, although we don't use a commercial firm.

 

It's based on the fact that there is always a certain amount of cell free foetal DNA in the maternal circulation, and so we (in the UK) just send a sample of maternal peripheral blood down to Filton, and Geoff Daniels and his simply amazing team do the rest.

 

The reliability is brilliant.

 

They do this even more in The Netherlands, where they work out if the mother requires, or does not require anti-D immunoglobulin prophylaxis at 28 weeks gestation based on this test.

 

I am SOOOOOOOOOOOOOOOO busy at the moment that I cannot cite any references, but will do so as soon as I can. 

Puget Sound Blood Center in Seattle, WA does a test like this.  We have sent them a couple of samples--one for a mom with anti-K and one for D.  Give them a call and they might be able to tell you someone in your half of the country that does it.  You can probably find their phone number somewhere on this page.

 

http://www.psbc.org/lab_services/index.htm

So then here is my next question....is it worth the extra cost (sounds like at least part of it has to be sent out); just to avoid pre-natal Rhogam in a small % of the population? 

 

My first thoughts were:

 

1.  Wouldn't it be easier and cheaper to do Rh Phenotype on Father (though as we know, that may not give a definitive Rh type of fetus; plus it can

     sometimes be difficult to get a definitive "father" to type...     ).

 

2.  While we know only about 15% of the population is Rh Negative, the fetus of an Rh Negative Mother must have a higher % chance of being Rh

     Negative (though I am not sure what that % is off the top of my head).  But am still thinking that this would only increase costs in that now, not

     only are you testing Mom and giving her Rhogam, but you have tested fetal cells in mom's sample (all of this, assuming the baby is Rh POS). 

     For the ones where the Fetus ends up being Rh NEG, you have saved the pre-natal Rhogam administration, but still have the cost of the new

     Test (which I would not think is cheap).

 

But I would really love to hear what people might think the pros and cons of such a test are/ would be (2 pros I can think of right off the bat would be the women who then avoid prenatal Rhogam; and knowing the risks of a fetus of a mom who has Anti-D, without having to do amniocentesis studies)??

 

Thanks

Brenda

The latest I heard on genotyping mom's blood for fetal Rh typing was that it is not avail in the US due to licensing issues. Maybe that has changed since Puget Sound is doing it (or are they sending samples to Europe for testing?)

Edited May 21, 201411 yr by marvy1

The latest I heard on genotyping mom's blood for fetal Rh typing was that it is not avail in the US due to licensing issues. Maybe that has changed since Puget Sound is doing it (or are they sending samples to Europe for testing?)

I was told by the Midwife (not Nurse practitioner) that called me, that her "small" Hospital does it (in which case, I don't know why she kept wanting us to do it; and has "suggested" to me that we start doing it)??  She said it is available.

Also, in doing my research, I asked 2 of the larger Hospitals I previously worked at in Calif., if they did it.  Neither are doing it.....and 1 of them made the comment that it has been used in Europe for years and is now available in the U.S.

Until I see/hear that some of the larger Hospitals even see the need to use it, I will not add it to my long to-do list.  But I would still be interested in hearing everyone's Pros and Cons....for my future consideration of the product.

Thanks so much,

Brenda

One of the biggest pros to this is that the anti-D that is injected is of human origin and of a finite source. For many reasons, avoiding injecting a product made of human plasma when it's not necessary would usually be considered to be advantageous.  And as the test is non-invasive, there's no harm to the foetus.As to whether it's cost-efficient, then I would think that depended on how many tests you carry out.  In Europe this has been one of the 'hot' topics for the last few years.

As for testing the father - don't even think about going there!

"The midwife's small hospital does the test."...........Hmmmm....Sounds fishy to me.

 

I wonder if she's all confused and is really talking about our regular old Fetal Maternal Hemorrhage (FMH) Test, since the FMH Test does pick up Rh Positive Cells (but in a post-partum specimen, not a pre-partum specimen.)  .....Just a thought.....

 

 

Donna

We have sent it out only in cases where the mom has an antibody.  In antibody cases where the dad is heterozygous or the antigen frequency makes it highly likely that he is heterozygous (whever he is) it seems justified.

Hi Brenda, this is an interesting situation; have you tried calling the mentioned "small hospital" and speaking to a blood bank rep directly?

"The midwife's small hospital does the test."...........Hmmmm....Sounds fishy to me.

 

I wonder if she's all confused and is really talking about our regular old Fetal Maternal Hemorrhage (FMH) Test, since the FMH Test does pick up Rh Positive Cells (but in a post-partum specimen, not a pre-partum specimen.)  .....Just a thought.....

 

 

Donna

Believe me; that was my 1st (and 2nd, and 3rd....) thought.  But she was adamant; then gave me the name of the company!  What still doesn't make sense to me though is why she wanted us to either do it, or find a place that could; if her Hospital does it (unless she was referring to a previous place she worked??).

 

One of the biggest pros to this is that the anti-D that is injected is of human origin and of a finite source. For many reasons, avoiding injecting a product made of human plasma when it's not necessary would usually be considered to be advantageous.  And as the test is non-invasive, there's no harm to the foetus.As to whether it's cost-efficient, then I would think that depended on how many tests you carry out.  In Europe this has been one of the 'hot' topics for the last few years.

As for testing the father - don't even think about going there!

That was the biggest pro that came to my mind also (maybe the only pro I could think of right now, while the test is probably "not" inexpensive).

 

Thanks

Brenda

Brenda

I heard about this company about 5 years ago, at that time only NY used the test. Myself and a few friends have encountered a few OB offices utilizing this testing, (not that often) it is still very expensive and not sure if the insurance companies are covering or out of pocket for those who are paranoid about blood based products. I know at one time it could not detect Rh in some blood types or something like that.

 

http://laboratories.sequenom.com

 

Hope everyone had a safe and great Memorial Day!

 

K

Thanks, Kimster.

 

OK.....So now I get it.  I can see the application In situations where a woman has Anti-D and has mated with man who is likely heterozygous for the Rho(D) gene.  If this new test can determine the Rh0(D) type of the fetus as early as 10 weeks of gestation, some individuals may use that information to decide whether to terminate the pregnancy.

As far as I am aware, 10 weeks gestation is too early for foetal genotyping.

 

We use 15 weeks gestation in the UK.

 

The other thing is, with Specialised Foetal Medicine Units able to "salvage" (hate the word, but that is the one in vogue) foetuses, when the mother has a gigantic anti-D quantification (>400 IU/mL, when we get worried about 20 IU/mL) or titre, why terminate?

Actually they do this on women who are not sensitized before 28 weeks. If the baby is negative (40% of the time with an Rh positive dad) then they would not have to have either dose of RhIG antenatal or post partum. And this would be in instances where they know for sure who the father is (10%) of all births are not the stated father in the US.

If you do a search of the internet of HDN a mother who is not knowledgeable about the high safety rate of plasma based products would be scared to death to have a RhIG injection let alone all the misinformation on vaccines. So there are moms that will pay for this test no matter what the OB says.

Sorry, my earlier post should have said 16 weeks, and not 15 weeks.

No one has suggested terminating a pregnancy but I'm sure everyone heaves a sigh of relief in finding that the fetus is K neg or D neg. I remember how easy it is to worry when pregnant.  It also obviates the need for repeat ultrasounds or titers.  It may also allow the birth to occur at the local 15 bed hospital instead of 150 miles away at the regional center.