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ELondon

Kell & Antibody screening

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Hi,

Hoping someone might be able to shed some light on the results from a 28 week prenatal blood test. My blood group is A Positive. As part of the standard testing they did an Antibody screening which came back abnormal. The Midwife told me it was for 'R1R1 K negative'. She said it was incredibly rare, and as she had only heard of 4 other cases with the same issue during her career, she was unable to give me any more information about it. Needless to say, I'm rather worried, even more so after consulting 'Doctor Google'.

This is my first pregnancy and I have never received a blood transfusion. I remember reading about ABO and Rh incompatibility in school but have never came across R1R1 or Kell before. Would I K positive baby in a K negative mother be an issue in a first pregnancy? At what point does the mother start developing antibodies, is it already in pregnancy or first at birth?

I had originally 'planned' a non medicated water-birth. In this case, would you say a C-section would be safer? I'm guessing that it would give the baby more rapid access to medical intervention.

Should I have my medical records updated to say my blood group is: R1R1 K negative?

I requested a print out of the results from the Midwife to see if it could help me get a better picture of the situation but I think it has just added to my confusion. 

The comments from the Bld Bank was:

RHK (Vision)

RHK CCee KNEG . Probable genotype R1R1 K negative.

Weak reactions contained in 26 out of 30 panel cells by IAT. We cannot exclude the presence of underlying alloantibodies. Please send in 3 EDTA samples for reference lab.

 

Group & Screen (+/- Crossmatch)

Group A POS

Ab. Screen Positive

 

Reactions in 26 out of 30 panel cells sounds very high to me. Is it cause for concern? Is Kell the same as alloantibodies?

Thanks in advance, most grateful for any replies. 

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PLEASE do not worry.  Your midwife is COMPLETELY wrong, and really should not comment about something she patently does NOT understand, and about which she has a pitiful amount of knowledge.  She should never have answered your questions with her lack of knowledge, but should have left it to your Obstetrician.

I note that you are a fellow "Brit"!

Within the British population, the percentage of people who have the R1R1 type (which is a type within the Rh Blood Group System) is 16%.  Also within the British population, the K- type (which is part of the Kell Blood Group System) is 91%.  What that means is that 91% of 16% of the British population is R1R1, K-, or, give or take, a few decimal points, 15% of the British population (about an eighth of the British population).  On Friday, 19th October 2018, the British population was measured as 66,690,116!  Let's call that 16.5 million in round numbers.  This means that, give or take, 9, 975, 000 in Britain are R1R1, K-.  Now, admittedly, your midwife will only be looking after women, but, even then, that means 4, 987, 500 women will have the same Rh type and K type as you!  How your midwife has only come across your "rare" type four other times in her career, is beyond belief (and I genuinely mean BEYOND belief), unless, as I say, her knowledge of blood groups and blood group serology is incredibly poor, and I repeat, she should NEVER have worried you like this.  Just in case you think that I do not know what I am talking about, I have worked in the field of blood transfusion/blood group serology for 43 years, have been an internationally invited lecturer and am the Chief Examiner in Transfusion Science for the Institute of Biomedical Science in the UK, and am a co-author of the British Society of Haematology's Guidelines for Blood Grouping and Antibody Testing in Pregnancy.  I don't write that to "blow my own trumpet", as it were, but to try to reassure you that I actually do know what I am talking about.

I should warn you that "consulting Dr Google" is equally as useless as listening to your midwife.

You should really relax.  YES, it is possible for you to produce red cell antibodies during your first pregnancy, but it is INCREDIBLY RARE.  It is even more rare for such an antibody to cause any problems in a first pregnancy.

I notice that the report from the Blood Bank was that they detected WEAK reactions with 26 of 30 panel cells, but they could not identify a specificity.  They have requested three further samples of blood to send to the Reference Laboratory.  Again, to give you some comfort, I hope, I ran a Reference Laboratory in London for 16 years before I retired in 2016, and we saw, quite literally hundreds of cases like yours.

For a red cell antibody to cause any problems within you pregnancy, it would have to have a titre of 32 or above (this means that it would still be detectable when it has been diluted THIRTY TWO times).  I can assure you that the mere fact that the Blood Bank reports weak reactions means that there is ZERO chance that the titre will be 32 or above.  If a Hospital Blood Bank, however big or famous the hospital may be, cannot identify an antibody, it is almost universal practice that samples will be sent to a Reference Laboratory for further testing - AGAIN, DO NOT WORRY ABOUT THIS.

There are many, many red cell antibodies that are clinically insignificant, both in terms of transfusion reactions and haemolytic disease of the foetus and newborn (which is what your midwife has left you worried about).

I KNOW it is difficult, but PLEASE do not worry.  PLEASE take no notice whatsoever of your midwife on this matter (I am sure she is an excellent midwife, but she is patently no expert in the field of blood groups), but DO talk to your Obstetrician, who, I hope, will have talked to your hospital's Haematology Consultant, who, in turn, will have spoken to the Consultant in Charge of the Reference Laboratory, and I am sure that they will echo my opinion that there is NOTHING to worry about.

Oh, and lastly, I am R1R1, K- myself!!!!!!!!!!!!!

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@Malcolm Needs: 

Thank you very much for your response, I can not describe in words how grateful and relieved I am. I have been so incredibly worried that I've not even slept since speaking with the midwife, and that was 36 hours ago. I really wish Google had a 'Pregnancy filter' that blocks any attempt to look up medical information.

I am under 'Midwife care' at the moment but will request a referral to an Obstretician for reassurance. This is my first pregnancy so I am still figuring out how the system works. I'm not familiar with the set up in other hospitals but the one I am registered with uses an app to send out test results. In my case I first had a message saying 'Abnormal blood test results, with no further details or comments" followed by a call from the midwife. I'm not sure what scared me the most, knowing that something abnormal had shown up on the blood test but not being able to see exactly what it was, or the call from the midwife saying how rare my blood type and antibodies are. I sincerely hope this is not the future of NHS medicine as I could very well have had a heart attack had a been a bit older.

I went to the hospital again today and submitted three further samples. Hoping and praying that they will come back normal. 

Thanks again for your input. I feel like a great weight has been lifted off my shoulders just from reading it. 

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Thanks ELondon.

Could I just say again, even if the Reference Laboratory does detect an antibody (or more than one, come to that), it is not a particularly abnormal thing in pregnancy, but it does not mean for one minute that the pregnancy will be affected; Mother Nature has seen to that.

There is another Blood Group System named Lewis.  The antigens within this system are soluble in the plasma part of your blood, and are adsorbed onto the red cells from the plasma (they are not intrinsic to the red cell membrane).  During pregnancy, the concentration of plasma lipoproteins (fatty proteins in the plasma) can increase enormously (about four-fold).  These plasma lipoproteins "mop up" the soluble Lewis antigens, and a pregnant woman, who would normally be, for example, Le(a-b+), can become Le(a-b-), and may even, temporarily, produce antibodies against the Lewis antigens (an individual hardly ever produces antibodies against an antigen that they express - but strange things happen in pregnancy!).  In addition, ALL babies are born as Le(a-b-), so any Lewis antigens Mum produces will NOT affect the baby!

There are many, many other antibody specificities that will not affect the pregnancy at all.

Now, I should say two things.  Firstly, I cannot say, from a distance, what is the antibody in your plasma (that can only be done by the laboratories at the Hospital and the Reference Laboratory, but it does not sound at all serious).  Secondly, i am what is called a Biomedical Scientist, not a doctor, and so I am, by Law, not allowed to diagnose (as far as I know, neither is the midwife), and this is why I am so glad that you are going to see an Obstetrician, who, I hope, will be able to reassure you even more.

Mean while, sleep easier, and enjoy your pregnancy!

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@Malcolm Needs Thanks for such a great response. I really appreciate you taking the time to share your knowledge. I have learnt a great deal just from reading your posts and am fascinated by the effect that pregnancy has on antibodies. Out of interest, do you happen know the 'false positive rate' for the Antibody tests carried out in pregnancy (around 28 weeks)? 

Many thanks,

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9 hours ago, ELondon said:

Out of interest, do you happen know the 'false positive rate' for the Antibody tests carried out in pregnancy (around 28 weeks)? 

I'm afraid my answer this time is going to be less helpful, because it very much depends upon the particular technology used by the laboratory, meaning that there is no single answer (and 28 weeks of pregnancy, from this point-of-view, is irrelevant - we would do the same tests at any stage during the pregnancy).

The majority of hospital laboratories use a technology known as column agglutination technology, or CAT.  With this, the reactants (for example, your plasma and a sample of donor red cells) are pipetted into what is known as a "reaction chamber" at the top of the column, after which the whole thing is incubated at 37oC (body temperature) for about 15 minutes, and the card is then centrifuged at a specific speed for a specific time (there is a bit more to it than that, but I don't want to go into too much detail and confuse the issue).  This type of technology is superb for detecting clinically significant antibodies, but can be prone to detect clinically insignificant "cold-reacting" antibodies, that will cause neither a transfusion reaction, nor problems with a pregnancy (haemolytic disease of the foetus and newborn).  These are sometimes called "false positives", although, strictly speaking, they are true positives, but not really the type of antibody we want to detect.  This is a bit of a nuisance (for us).

There are loads of other technologies and techniques, but the Reference Laboratories will have access to almost all of these.  In addition, the Reference Laboratories will have access to many more examples of rare red cells and grouping reagents.  In a case like yours, I would think that the Reference Laboratory would first work out the actual specificity of your antibody, and then perform tests (probably in good, old-fashioned test tubes) to see whether the antibody reacts at 37oC or at a lower temperature.  This will tell them whether or not your antibody will need to be monitored throughout your pregnancy.  I would be very surprised, given what you have told us about your case, if the Reference Laboratory would require another sample during your pregnancy, as 28 weeks of pregnancy is thought of as a sort of "cut off" point - BUT, I must reiterate, I am commenting "from afar", for one thing, and, in any case, am not allowed to diagnose or give specific advice to your case.

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