K-B stain

[bbbirder]

We have been having a discussion about when a Kleihauer-Betke stain (or even flow cytometry for fetal cells) becomes a worthwhile test to perform.

We already do not perform a fetal screen (rosette test) at less than 20 weeks gestation, and only give one vial of RhIG (300mcg), assuming that the fetal blood volume is less than 30 mls prior to 20 weeks.

 

However, in the case of trauma to the mother, the doctors often want a KB stain.  I have not been able to find any reference that states it is of no value to do before XX weeks gestation.  I assume there is one, where even if the fetus was exsanguinated, you would be unlikely to detect it in the mother's blood.

 

Any thoughts?

 

Thanks,

Linda

 

[David Saikin]

The docs are looking for  a compormise in the placental circulation, which may indicate some future problems for the fetus or mother.  We also have docs that use the KB before and after fetal versions - for the same reason.

[Malcolm Needs ☆]

In the UK, BCSH Guidelines state that an FMH is not required before 20 weeks gestation, as the standard does of anti-D immunoglobulin will cover the mother for entire volume of an entire foetal bleed.

[tbostock]

I read (somewhere) that a fetal-maternal bleed in trauma is the #1 indicator of fetal demise (or at imminent delivery).

We're still struggling with the decision on whether to do KB stains here; we are a trauma center and they have asked for it in the past.

[R1R2]

We have been having a discussion about when a Kleihauer-Betke stain (or even flow cytometry for fetal cells) becomes a worthwhile test to perform.

We already do not perform a fetal screen (rosette test) at less than 20 weeks gestation, and only give one vial of RhIG (300mcg), assuming that the fetal blood volume is less than 30 mls prior to 20 weeks.

 

However, in the case of trauma to the mother, the doctors often want a KB stain.  I have not been able to find any reference that states it is of no value to do before XX weeks gestation.  I assume there is one, where even if the fetus was exsanguinated, you would be unlikely to detect it in the mother's blood.

 

Any thoughts?

 

Thanks,

Linda

I didn't think you could do a rosette test predelivery, regardless of gestation age?

[David Saikin]

I didn't think you could do a rosette test predelivery, regardless of gestation age?

I think the original question is about trauma to the mother.  The rosette has nothing to do with a KB in this scenario . . . the rosette only looks for Rh+ cells while the KB looks for fetal hgb . . . as Terri and I have said,  the docs are looking for fetal cells in the mother indicating the placental circulation has been compromised and therefore complications to the pregnancy may occur.

[Auntie-D]

We will do one on women who have had trauma regardless of rh status if the clinicians state that it will affect treatment of the mother/foetus. We would also do for a coroners case, but not less than 'viable' gestational age.

We will do one on women who have had trauma regardless of rh status if the clinicians state that it will affect treatment of the mother/foetus. We would also do for a coroners case, but not less than 'viable' gestational age.

[kirkaw]

David/R1R2,

If a known Rh negative woman presented in the ER with some sort of trauma with a gestational age of 18 weeks, would a K-B stain or rosette test be appropriate? Or both?

Thanks,

Amelia

[R1R2]

For determination if fetal bleed occurred a KB should be ordered.  For RhIG administration, neither test is required becuase 1 vial should cover any amount of bleed. 

[Malcolm Needs ☆]

I would love to agree with you R1R2, but I cannot.

There are so many different doses of anti-D immunoglobulin available (250IU, 500IU, 1500IU, 2500IU, to name but a few) that it is still necessary, in my opinion, to estimate the foeto-maternal haemorrhage, either by KB or by flow cytometrey, to ensure that the dose of anti-D is sufficient.

[R1R2]

I agree Malcolm.  I thought of that right after I clicked on "Post".   May answer is based on a 300 mcg (or 1500 IU) dose. 

[AMcCord]

David/R1R2,

If a known Rh negative woman presented in the ER with some sort of trauma with a gestational age of 18 weeks, would a K-B stain or rosette test be appropriate? Or both?

Thanks,

Amelia

 

The rosette test would not be appropriate because you don't know the Rh type of the fetus. Rosettes are formed around Rh Pos fetal cells, so if the fetus in your trauma case is Rh neg, the rosette test would not detect the bleed.

[Auntie-D]

The theory is that at less than 20 weeks 250iu is enough to cover any possible bleed that the foetus may have...

[Auntie-D]

With respect Malcolm - those are the latest Guidelines regardless of our opinion

[kirkaw]

Let me be more direct as to why I'm asking the question. We stock both the 1500IU Rhogam product and the 250IU Rhogam product. The ER uses quite a bit of the smaller dose. Our policy is that the 250 IU product is to be used for Rh- women at less than 12 weeks gestation. Prior to issue of this product, we perform a blood group and type and antibody screen.

If a provider, ER or OB orders the larger dose, which is designated for a pregnant woman, at more than 12 weeks gestation, we perform a blood group and type, and antibody screen and the fetal screen (rosette test). Of course if the rosette test is positive, we would do the K-B stain.

The questions have come up, A) do we really need to stock the smaller dose of Rhogam and for women greater than 12 weeks who present in the ED, assuming their ER visit is related to a threatened pregnancy, do we need to perform the rosette test or K-B stain to make an assessment for Rhogam administration. When I suggested the K-B stain, the ER docs did not want to wait for it.

[Auntie-D]

But the KB stain is to see if any additional anti-d is required... Issue the anti-d at the desired volume, do the KB and then you have 3 days to give more, if needed.

[AMcCord]

If the rosette test was positive, a K-B would be necessary to determine RhoGAM doseage. Of course if the gestational age is low enough the rosette test would not be positive anyway, unless possibly the pregnancy was multiples.

[David Saikin]

I have only ever stocked the large dose of RhIg - why risk giving the smaller dose. The cost is the same (for me anyway) so I'm not harming the pt/mother in anyway with the larger dose (300ug)regardless of gestational age. As I stated above - the KB stain looks for fetal cells; the docs want to see if the placental circulation is compromised. Forget the rosette. (and I forget the samller dose; the docs have no choice in the mattter and I have never had a problem in a 700+ bed tertiary care hosp with busy ED and neonatal unit; a 350+ bed with busy maternity/ED; and a small 24 bed with busy Maternity/ED). Give the docs what they need 'cuz they are not always correct in what they want.

[R1R2]

I have only ever stocked the large dose of RhIg - why risk giving the smaller dose. The cost is the same (for me anyway) so I'm not harming the pt/mother in anyway with the larger dose (300ug)regardless of gestational age. As I stated above - the KB stain looks for fetal cells; the docs want to see if the placental circulation is compromised. Forget the rosette. (and I forget the samller dose; the docs have no choice in the mattter and I have never had a problem in a 700+ bed tertiary care hosp with busy ED and neonatal unit; a 350+ bed with busy maternity/ED; and a small 24 bed with busy Maternity/ED). Give the docs what they need 'cuz they are not always correct in what they want.

I like your last sentence!

[RR1]

We also need to factor in maternal height/ weight (BMI)- which we have never done before in the UK, and this too could affect efficacy of the dose administered. I know there is new guidance on this issue.

[David Saikin]

 

We also need to factor in maternal height/ weight (BMI)- which we have never done before in the UK, and this too could affect efficacy of the dose administered. I know there is new guidance on this issue.

 

this question is not about dosing RhIg . . . it is about the usefulness of the KB stain in determining if there will be complications to a pregnancy after an abdominal trauma. The presence of fetal cells is an indicator that alerts the physician that some sort of complication may follow. It has nothing to do with the mother's blood type or that of the fetus. If concerned you can always recommend a full dose if the pregnancy is less than 20 weeks (and that is a whole 'nother story as to when a rosette needs to be done - but not at this time or place).

[RR1]

Perhaps this reference may help ? from the attached FMH (UK ) guidelines

 

Samadi R, Greenspoon JS, Gviadza I, Settlage RH, Goodwin TM. Massive fetomaternalhaemorrhage and fetal death: are they predictable? Journal Perinatology 1999;
19(3): 227-9

 

BCSH_FMH_bcsh_sept2009.pdf