Case 40 – summary

In this case we were able to interpret blood grouping cards, to allow us to determine further management for this pregnant lady.

The first sample to interpret was the blood group of the pregnant lady which identified that she was group O RhD negative.

image

Incubate the patients erythrocytes with antibodies to known antigens (column 1 – Anti-A, column -2 anti B and column 3 – anti-D) and also mix the patients plasma with erythrocytes of known blood groups (column 5 – group A1, and column 6 – group B)

When agglutination has occured (i.e. when anti-A reacts with an erythrocyte of group A) the aggluntinate stays at the top of the gel.  If no agglutination occurs – the red cells will fall to the bottom of the gel.

In this case – there is no evidence of agglutination with anti-A or B therefore the red cells do have these antigens present.  There is also no agglutination with anti-D.

Agglutination is present in columns 5 and 6 which indicates that both anti-A and anti-B are present in the patients serum.  Combining all these results together we can established that this patients blood group is O Rh negative.

Anti-D guidelines

NICE guidelines state that all RhD negative women should be offered routine prophylaxis with anti-D during the 3rd trimester.

Following a sensitising event, anti-D Ig should be administered within 72hrs of the event (although some protection may be offered if given within 10 days)

BCSH guidelines:

Sensitising events include

  • amniocentesis/chorionic villous sampling, cordocentesis
  • antepartum haemorrhage/uterine bleeding
  • external cephalic version
  • abdo trauma
  • ectopic pregnancy
  • evacuation of molar pregnancy
  • IUD/stillbirth
  • In utero therapeutic intervention
  • Miscarriage/threatened miscarriage (heavy/repeated bleeding/pain)
  • Termination
  • Delivery – normal/instrumental/c-section
  • Intraoperative cell salvage.

If pregnancy <12 weeks – minimum dose of 250iu

12-20weeks – minimum dose 250iu

>20 weeks – minimum dose 500iu – at this point test for FMH(fetomaternal haemorrhage) is required.  If <4mls no further treatment required.  If greater than 4mls, further dosage of anti-D should be given – calculated at 125iu IM per ml of fetal red cells detected.

Prophylaxis:

Either: single dose at 28 weeks.

Or: 2 dose regime at 28 and 34weeks

At this point a second group and screen sample should be taken for repeat antibody screen.

This prophylaxis should be given, regardless of any previous anti-D treatment during pregnancy.

Following delivery ABO and RhD typing should be taken from cord blood.  If the baby is RhD positive, anti-D 500iu IM should be administered to mother, followed by testing for FMH.

Preventing antibody formation:

  • All D negative female of child bearing age should receive D negative and where possible K-negative blood.
  • Anti-D prophylaxis during pregnancy
  • Where possible, D negative platelets, should be tranfused to D negative girls and women (if only D positive available, prophylaxis should be given).

Finally, blood grouping was performed for the baby.

image

This illustrated that the baby was also ORhD negative.  And as suggested by some of the followers, we would not usually perform a reverse group on the baby, as at this stage ‘naturally occuring antibodies (i.e. anti-A and anti-B in this case) have not yet formed.

Other clinical conditions that may produce a similar findings include

  1. patients who are immune compromised,
  2. following trauma with major haemorrhage, where patients are often transfused O red cells, and AB plasma,
  3. lab error could also be a possibility.

Thank you for your contribution on this case!

Also refer to:

BCSH guideline for the use of anti-D immunoglobulin for the
prevention of haemolytic disease of the fetus and newborn http://www.bcshguidelines.com/documents/BCSH_Anti-D_Guidelines_Published_Trans_Med_Jan_14.pdf

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One Response to Case 40 – summary

  1. Tom says:

    K negative always for under 50 females. One dose anti-D at 28 weeks only is for the 1500 IU anti-D. All fmh bleeds over 2mL are sent off for flow cytometry fmh usually at nhsnt

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