Pos Fetal Screen + Neg Kleihauer-Betke?

[SANDRA CORBETT]

Hi Patty,

The Immucor Fetalscreen kit has a problem. Immucor acknowleges that it may be the indicator cells in the kit that are causing a false positive reaction. Note the results of the last CAP Survey, in which 66% of the participants got a positive result, when it should have been negative. The kit is yielding a positive result when there has been no fetal bleed (No D or Du pos baby cells in Mother's circulation.)

[PBryant]

Sandra,

We have also experienced problems with the Immucor Fetal Bleed Screen and you are correct when you stated they will acknowledge the problem over the phone. We had two cases this weekend of positive screens with negative K-B stain. Both patients were Du negative and DAT negative. One case was resolved by retesting and using manual washing technique instead of using our cell washer. The other case stayed positive inspite of the manual wash. It has been noted on the K-B stain for this patient that there was a marked presence of WBCs and platelets. Review of the CBC results did show and elevated WBC count and a normal platelet count. The immucor representative as ked that we send them the sample involved in the false positive so we will see what they can find out.

[rcurrie]

Hey Patti,

Glad to see you in this forum. Since I am no longer in the Blood Banking business, I pass the QA baton to you.

As far as the FBS discussion goes, my guess is the anti-D is cross-reacting with a determinant on WBCs. As most of us old heads know, washing is quite an effective method of removing WBCs. Difficult pregnancies often result in high WBC counts for the mom.

BC

[SANDRA CORBETT]

Thanks for this email. I was starting to believe that I was the only one out there that knew about Immucor's problem. Even CAP did not know, as evidenced by their response on the Survey. CAP wanted to receive a letter from us, and I guess I will have to write one. Take care, Sandy

[KLBennett]

I recently started working at a small hospital in WA that is designated critcal access and therefore performs a broad range of testing considering it's size.

One of the first things they asked me to trouble shoot was a positive Proficiency test result with their immucor fetal screening kit. What I determined through multiple runs of the same sample and qc cells was that inadequate washing was the culprite. They use 10X75 tubes even though the manufacturer recommends 12x75. Increasing the the number of washes, either manually or automatically, eliminated the false positive. The reactivity of the negative qc cell was not affected by the fewer washes but the positive qc cell was. The fewer washes performed the more rosettes seen in the positive cell and proficiency sample.

[rescyth]

if you got either Du positive Mom and Baby, it's better to proceed to KB staining. Du POS MOM will give you false POS FS and Du Negative baby will give you false negative FS. To determine if mom is really Du Pos or the weak pos is cause by infants RH pos cells, wash the specimen about 4x with saline, baby or newly formed cells usually has a less specific gravity and settles at the top most after spinning, so it is easily wash out after decanting.

[Mary Ann]

The FBS will detect rh pos cells,your mom is weak D,cannot use test. The KBstain is used-neg would equal 1 vial.

[Fluffy agglutinates]

I realise this is an old post but I have to ask: Why would you give prophylactic anti-D to a woman who is D positive? This is completely against our guidelines here in the UK. Is it different in the US? People with weak D cannot make allo anti-D. D+ is D+ whether weak or not.

Someone who is a partial D is highly unlikely to react 'weakly' with anti-D; they are either strongly pos or completely neg. The only D variant of concern, with respect to anti-D stimulation, is DVI & that shouldn't be picked up as positive in any patient testing (as the anti-D you use should not react with DVI).

[AMcCord]

Giving RhoGAM to weak D positive patients is not an uncommon practice in the US. It's a very conservative approach. (I understand that we also give larger doses of RhoGAM.) Don't forget one very big difference between your medical system and ours - many, many medical malpractice lawsuits. Medicine is practiced here in an increasingly defensive mode - sad, but true.

[Fluffy agglutinates]

Crikey, that is sad! What about when the weak D patient complains about getting an unnecessary injection of human-sourced product?!

I wouldn't like to have to work that way. Guess we're lucky over here...

[Malcolm Needs ☆]

I realise this is an old post but I have to ask: Why would you give prophylactic anti-D to a woman who is D positive? This is completely against our guidelines here in the UK. Is it different in the US? People with weak D cannot make allo anti-D. D+ is D+ whether weak or not.

Someone who is a partial D is highly unlikely to react 'weakly' with anti-D; they are either strongly pos or completely neg. The only D variant of concern, with respect to anti-D stimulation, is DVI & that shouldn't be picked up as positive in any patient testing (as the anti-D you use should not react with DVI).

I'm sorry Fluffy agglutinates, but you are incorrect on both counts!

Individuals with Weak D can and do make alloanti-D (Joyce has verified this at the IBGRL), and some partial D phenotypes give a very weak reaction with anti-D reagents (although not as weak as does a Del).

You will also find that some hospital laboratories test cord red cells with an anti-D that will detect partial DVI and will give anti-D immunoglobulin prophylaxis if this test is positive (although they do not necessarily type the mum with this anti-D first to see if the baby inherited it from her)!

:redface::redface:

[Fluffy agglutinates]

Ah yes, I have read about those but you must agree they are infinitely rare & it would be a waste of resource to change guidelines on the strength of them.

The stance I am taking is from our UK guidelines & I still think it is daft to give prophylaxis when the Mum is a weak D!

Where do you draw the line at what is weak? 3+/ 2+/ 1+ etc? In this case I would be much more interested in confirming the patient D type (i.e. checking for partial D) before 'liberally applying' anti-D proph.

As for those hospitals of yours testing for DVI in babies they are being very naughty!

[Malcolm Needs ☆]

Ah yes, I have read about those but you must agree they are infinitely rare & it would be a waste of resource to change guidelines on the strength of them.

The stance I am taking is from our UK guidelines & I still think it is daft to give prophylaxis when the Mum is a weak D!

Where do you draw the line at what is weak? 3+/ 2+/ 1+ etc? In this case I would be much more interested in confirming the patient D type (i.e. checking for partial D) before 'liberally applying' anti-D proph.

As for those hospitals of yours testing for DVI in babies they are being very naughty!

Yes, they are very rare and giving anti-D immunoglobulin prophylaxis in such cases would probably be a waste of time. Certainly, I would not change the Guidelines.

I was much more concerned, however, about your statement about Partial D types either reacting strongly with anti-D typing reagent, or not reacting at all. THIS IS JUST NOT TRUE.

:(:(

[jcdayaz]

Yes, they are very rare and giving anti-D immunoglobulin prophylaxis in such cases would probably be a waste of time. Certainly, I would not change the Guidelines.

I was much more concerned, however, about your statement about Partial D types either reacting strongly with anti-D typing reagent, or not reacting at all. THIS IS JUST NOT TRUE.

:(:(

I concur with Malcolm. You can potentially get all different strengths of D reactions depending on which partial/mosiac/etc types you are dealing with.

We do all our testing in gel..so even weak D's and Mosaics typicaly react @2+. We would just result them as Rh Pos.

It never hurts to give a patient Rhig if they didn't really need it...It does hurt the patient if you don't give it when they do need it!!

[Fluffy agglutinates]

Blimey a telling off from the Master!

Ok perhaps I was being a little simplistic in my response (it's difficult in a forum!).

If I got anything less than a 4+ reaction with my anti-D then I would perform a partial D typing panel to find out what it truly was - A thing that seems to be missing in the case that started this thread. There seems to be no interest in finding that out.

And I DO think that it is very irresponsible to give out anti-D to people who don't need it. It is a human sourced product that potentially contains allsorts of contaminants! Secondly we do not have an endless supply of this stuff to waste...

[jcdayaz]

Blimey a telling off from the Master!

Ok perhaps I was being a little simplistic in my response (it's difficult in a forum!).

If I got anything less than a 4+ reaction with my anti-D then I would perform a partial D typing panel to find out what it truly was - A thing that seems to be missing in the case that started this thread. There seems to be no interest in finding that out.

And I DO think that it is very irresponsible to give out anti-D to people who don't need it. It is a human sourced product that potentially contains allsorts of contaminants! Secondly we do not have an endless supply of this stuff to waste...

In the UK is your source of "AntiD" not Rhogam? Ours is and has been proven to be VERY safe.

I have seen several presentations, back in the day of tube testing, of both weak D's and mosaic D's present with an Anti-D. Yes, very rare...but I have seen it.

[clmergen]

I never do partial D testing nor do we do weak D testing, except as required. If the patient is D neg on immediate spin or on the Echo, we call them D negative and give Rh Immune globulin.

[adiescast]

We don't have a "partial D typing panel." The patient either reacts with the antisera we have or they don't. We also do not perform a weak D test routinely on the mother, although your point about where the baby got it from is well taken. The OB physicians are VERY sensitive to potential legal issues and the chances of being sued over a woman developing a "preventable" (HA!) anti-D are much higher than the chances of being sued for an adverse effect from trying to prevent development of anti-D. Plus the statute of limitations for OB cases is VERY long.

[AMcCord]

And (correct me if I'm wrong on the time frame) the child can sue (or someone can sue on their behalf, if a minor) until they are 21 years old for 'damage' suffered as a result of something that can be connected somehow with mom's pregnancy or delivery. So, if mom has an anti-D that "should" have been prevented and baby suffers for it, the doctor is on the hook for it for a long time and potentially for many, many dollars.

[Malcolm Needs ☆]

Blimey a telling off from the Master!

A very flattering comment, but hardly true! In the UK alone there are people like Neil Avent, Dave Anstee, Geoff Daniels, Joyce Poole, Pete Martin, Louise Tilley, Marion Scott, to name but a very few, with whom I would be happy to be mentioned with in the same breath, and that is just in the UK, and just talking about Rh.

I'm very happy to still be an awed pupil in their presence.

:D:D

[jcdayaz]

And (correct me if I'm wrong on the time frame) the child can sue (or someone can sue on their behalf, if a minor) until they are 21 years old for 'damage' suffered as a result of something that can be connected somehow with mom's pregnancy or delivery. So, if mom has an anti-D that "should" have been prevented and baby suffers for it, the doctor is on the hook for it for a long time and potentially for many, many dollars.

I believe you are correct. My husband is a pediatric ophthalmologist. In dealing with the pediatric population he has mentioned in the past the potential "legal issues" he could be faced with if he botches a surgery or whatever. I have heard reference to the 21 age limit several times. I would presume it to be universal among all types of pediatric practices.

[jcdayaz]

Are you using the Imucor fetal Screen kit? It has a problem that the manufacturer has not disclosed to users yet. Note that 66% of the participants on the last CAP survey got the negative fetalscreen incorrect. They called it positive, and the fetal cell stain was negative. We have stopped using the kit and reverted to Kleihauer's in house with the Simmler kit until Immucor can resolve its problem. Negative tests are OK. There are no cases of false negatives I guess I will write a letter to CAP. I told them about it, Immucor is silent and studying the problem (they will acknowledge the problem over the phone), and Cap needs a letter to the Chair.

We have had multiple presentations of + fetal screens with Immucor and negative Kleihauer's. After the trend was recognized, we called Immucor. Their response was "If the patient's reaction is not AT LEAST as strong as the positive control, call it negative".

[L106]

We have had multiple presentations of + fetal screens with Immucor and negative Kleihauer's. After the trend was recognized, we called Immucor. Their response was "If the patient's reaction is not AT LEAST as strong as the positive control, call it negative".

WHAT ???

I have seen many Positive patient FMH tests that also gave Positive Kleihauer results, but I have never seen an patient DMH test be as strong as the Positive Control.

[jcdayaz]

WHAT ???

I have seen many Positive patient FMH tests that also gave Positive Kleihauer results, but I have never seen an patient DMH test be as strong as the Positive Control.

Yep, VERY SCARY advice from Immucor, to say the least. I believe a former post...there must be some "issue" going on with the fetal screen kits that we are not being told about.

Although I will say we were getting @ 25% + fetal screen tests with only a SMALL number of + Kleihauer's...probably only 1 or 2% in the last 6 months..... So we "relaxed" our gudeline to calling a FS test positive....not as much as the manufacturer recommended, of course.

[L106]

Although I will say we were getting @ 25% + fetal screen tests with only a SMALL number of + Kleihauer's...probably only 1 or 2% in the last 6 months..... So we "relaxed" our gudeline to calling a FS test positive....not as much as the manufacturer recommended, of course.

When you say you "relaxed" your guideline to calling a FS test positive ...... Are you saying that you are not following the guidelines stated in the Fetal Screen Test's manufacturer's insert?