London Regional Transfusion Committee

Blood Grouping and Antibody Testing in Pregnancy

Training Presentation by iTransfuse with the London RTC

Based on the BCSH Guideline for Blood Grouping and Antibody Testing in Pregnancy 2006

London Regional Transfusion Committee

Aim

• By the end of this you should have an understanding of:– The tests required during pregnancy– Why we do the tests– What antibodies are significant– What tests are required post delivery

London Regional Transfusion Committee

Purpose of Lab Testing

• ABO and D typing to identify D negative women who need anti-D

• Antibody screening and ID of red cell alloantibodies

• Monitor circulating levels of clinically significant antibodies

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Haemolytic disease of the Newborn

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Antenatal Testing Protocols

• Booking sample testing (ABO and antibody screen)– ideally at 10-16 weeks gestation

• Repeat test at 28 weeks gestation (ABO and antibody screen)

• If antibody screen is positive a full antibody investigation must be performed

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Clinically Significant Antibodies

• What antibodies are implicated in severe HDN?– Anti-D– Anti-c– Anti-K

• In addition to these anti-C, -E, -Fya and Jka

• Only IgG antibodies are capable of entering the foetal circulation

London Regional Transfusion Committee

Women with anti-D• How can you distinguish between prophylactic

and immune?– Check transfusion records• Previous prophylactic anti-D given (within 8 weeks)• Antibody history?• Phone ward/GP to check if patient transferred

– Send for D Quantitation• Anti-D level rarely exceeds 1 iu/ml post prophylaxis

unless a dose of more than 1250 iu has been administered

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Immune Anti-D

• How often should you test during pregnancy?– Every 4 weeks until 28 weeks gestation then every

2 weeks until delivery• What testing should be done?– Maternal Rh phenotyping– Anti-D quantitation (every maternal sample)– Partner sample phenotyping

• Refer patient to Obstetric team

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Concentration of Anti-D

• What levels of anti-D are significant?

Anti-D Level HDN?

<4 iu/mL Unlikely

4-15 iu/mL Moderate risk

>15 iu/mL High risk of Hydrops fetalis

London Regional Transfusion Committee

Women with anti-c

• How often should you test during pregnancy?– Every 4 weeks until 28 weeks gestation then every

2 weeks until delivery• What testing should be done?– Maternal Rh phenotyping– Anti-c quantitation (every maternal sample)– Partner Rh phenotyping

• Refer patient to Obstetric team

London Regional Transfusion Committee

Concentration of Anti-c

• What levels of anti-c are significant?

Anti-c Level HDN?

<7.5 iu/mL Unlikely

7.5-20 iu/mL Moderate risk

>20 iu/mL High risk of sever HDN

London Regional Transfusion Committee

Women with anti-K

• How often should you test during pregnancy?– Every 4 weeks until 28 weeks gestation then every

2 weeks until delivery• What testing should be done?– Maternal Kell phenotyping– Anti-K Titre (every maternal sample)– Partner Kell phenotyping

• Refer patient to Obstetric team

London Regional Transfusion Committee

Women with other red cell antibodies

• Anti-C, -E, -Fya and –Jka are other antibodies most associated with HDN

• Other blood group antibodies have been implicated in HND

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Women with other red cell antibodies

• How often should you test during pregnancy?– Booking and 28 weeks

• What testing should be done?– Antibody investigation– Maternal phenotyping– Titre the antibody against previous sample– Partner phenotyping

• Refer patient to Obstetric team

London Regional Transfusion Committee

Paternal Testing

• Why do it?– Helps predict the likelihood of the foetus carrying

the relevant red cell antigen– For example. Maternal phenotype c- and anti-c

detected. Paternal phenotype Cc. Foetus has 50% change of carrying antigen.

• Caution – is the partner the father?

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Foetal Genotyping

• When should you send samples?– When a clinically significant antibody of high concentration

is present– Women has history of HDN and father is heterozygous for

relevant antigen

• What antigen(s) can be determined?– D– c– K– (E)

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At Delivery – D negative women with no immune anti-D

• What samples are required?– Maternal and Cord blood

• What tests should be done?– ABO and Rh typing on both samples– FMH estimation (flow cytometry / Kleihauer)– DAT?

• When do you give anti-D prophylaxis?– When baby is RhD positive

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Future Developments

• Mass testing for foetal blood group antenatal for RhD negative women

• If done before 28 weeks it would prevent the use of anti-D prophylaxis in women carrying RhD negative foetus’s

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Acknowledgement

• This educational resource has been produced to support education and training by the London RTC Education Resource group.

• Please acknowledge the working group when using or adapting this presentation during delivery.

• Please contact the RTC Education Resource group if you have ideas for other presentations or would like to be involved.

• Thank you