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Introduction
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A blood sample is taken from all pregnant women at their first antenatal visit to:
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- Test for the presence of red cell antibodies
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- Establish ABO and Rh D blood groups
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If no antibodies are detected, a repeat sample for the same tests is requested in the third trimester, usually at 26 weeks gestation.
A very small number of women are found to have antibodies which are more likely to affect the baby, e.g. anti-D, anti-c and anti-K. More frequent samples will be requested if these antibodies are present, or if there is any other cause for concern regarding baby's well being.
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The objectives of routine antibody testing in pregnancy are to:
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- detect and identify red cell antibodies
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- identify Rh D negative women who need anti-D immunoglobulin prophylaxis
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- identify pregnancies at risk of fetal and neonatal haemolytic disease resulting from clinically significant maternal antibodies crossing the placenta and entering the fetal circulation
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When clinically significant red cell antibodies are present during pregnancy the purpose of follow-up antibody testing is to:
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- identify the fetuses that may require treatment before term
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- predict which infants might require treatment and should be monitored more closely after birth
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- detect new antibodies since those who develop one antibody are more likely to develop additional antibodies
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If an antibody is confirmed and is of clinical significance to the fetus, the antibody will be quantified or titrated and follow-up tests performed as recommended.
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The follow-up investigations are:
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- monitoring maternal red cell antibody levels
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- identifying possible additional antibodies
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- red cell phenotyping and genotyping (DNA analysis) the father when necessary
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- fetal genotyping if required
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Guide to routine red cell antibody screening
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The results of the 1st screen at booking, guides the management pathway:
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- those women with any Group 1 or Group 2 antibodies detected are to be referred to the Maternal Fetal Medicine Program for ongoing care
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- women with Group 3 or no antibodies detected can continue routine care
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Women whose blood group result is RhD Negative may be eligible to receive RhD immunoglobulin.
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Any concerns or queries should be raised with the on-call haematologist.
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Pregnancy Booking Clinic - All Women
| - Blood Group
- Red cell antibodies
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| | Repeat antibody screen on all women at:
| - 26 week visit at the Women's or Community Clinics
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| Group 1 antibody detected:
| (-D, -c, -E, -e, -C, -Fya, -K, -k)
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| Group 2 antibody detected:
| (-Cw, -Fyb, -Jka, -Jkb, -Lua, -Lub, -S, -s, -M)
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| Previous History of HDN:
| Refer to MFM Program for pregnancy management
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|  | Group 3 antibody detected
| (-P1, -N, -H, -Lea, -Leb, -Lea+b, -Sda, -Bga, -Bgb)
| Repeat antibody screen at 26 weeks
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Royal Women's Hospital Clinical Practice Guidelines (CPGs) are intended to provide guidance to health care professionals, based on a thorough evaluation of research evidence, on the practical assessment and management of specific clinical issues or situations. The guidelines allow some flexibility on the part of the health care professional based on the needs of the specific patient for whom they are caring.
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Please remember to read our disclaimer.
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