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

London Regional Transfusion Committee Haemolytic disease of the Newborn

London Regional Transfusion Committee Antenatal Testing Protocols Booking sample testing (ABO and antibody screen) – ideally at weeks gestation Repeat test at 28 weeks gestation (ABO and antibody screen) If antibody screen is positive a full antibody investigation must be performed

London Regional Transfusion Committee Clinically Significant Antibodies What antibodies are implicated in severe HDN? – Anti-D – Anti-c – Anti-K In addition to these anti-C, -E, -Fy a and Jk a 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

London Regional Transfusion Committee 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

London Regional Transfusion Committee Concentration of Anti-D What levels of anti-D are significant? Anti-D LevelHDN? <4 iu/mLUnlikely 4-15 iu/mLModerate risk >15 iu/mLHigh 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 LevelHDN? <7.5 iu/mLUnlikely iu/mLModerate risk >20 iu/mLHigh 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

London Regional Transfusion Committee 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?

London Regional Transfusion Committee 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–D –c–c –K–K – (E)

London Regional Transfusion Committee 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

London Regional Transfusion Committee 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

London Regional Transfusion Committee 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