Rhesus Isoimmunizaton and Anti-D Flashcards
What does RhD positive or negative mean?
The presence of the RhD antigen on human red blood cells.
Describe the circumstances where a mother may require anti-D
If a mother is RhD negative and her baby is RhD positive due to inheriting father’s blood type.
If fetal blood enters maternal system an immune response can be mounted and antibodies are produced. This is called sensitisation. If mother is exposed to an RhD positive antigen she is likely to mount a greater response which increases the risk of miscarriage, stillbirth and aneamia in baby.
Why may fetal anaemia occur following a sensitising event?
Antibodies from the mother cross the placenta and bind to fetal red blood cells. Fetus removes these from system which can lead to fetal anaemia.
When can a sensitisation event happen?
Any time in the pregnancy but in particular: Trauma ECV Amniocentesis APH Late miscarriage
Why does rhesus isoimmunisation lead to jaundice?
When antibodies produced by the mother bind to fetal red blood cells, fetus has to break these down. After birth there is a lot of red blood cells to break down which releases bilirubin and can lead to pathological jaundice.
What can fetal anaemia lead to?
Heart failure, swelling, IUD
How can haemolytic disease of the newborn be prevented?
By using anti-D
What does Anti-D do?
Neutralises the fetal antigen which prevents the mother’s body from mounting a response.
When is Anti-D administered?
NICE 2008 suggests routine administration of Anti-D at 28 and 34 weeks in addition to additional dosages if any risk factors occur.
What is the new test?
Cell Free DNA test which is a blood test taken at 16 weeks for all RhD negative women to check the fetus. If negative then no routine anti-D prophylaxis necessary. Blood are taken at delivery to check.
