Rhesus disease can be avoided if sensitisation is prevented. If an RhD-negative woman has not been sensitised to RhD-positive blood, an injection of anti-D immunoglobulin can prevent her being sensitised.
Anti-D immunoglobulin
Sensitisation is avoided by administering anti-D immunoglobulin. The anti-D immunoglobulin neutralises any foetal RhD-positive antigens that have entered the mother’s blood. If the antigens have been neutralised, the mother’s blood will not start to produce antibodies.
You will be offered anti-D immunoglobulin after a potentially sensitising event, during which some foetal RhD antigens may have entered your blood. For example, if you experience any bleeding during your pregnancy, if you have an invasive procedure (such as amniocentesis) or experience any abdominal injury, anti-D immunoglobulin may be administered.
Anti-D immunoglobulin can also be administered routinely during the third trimester of your pregnancy. It is more likely for small amounts of foetal blood to pass into your blood during this time even if there have been no noticeable sensitising events. This routine administration of anti-D immunoglobulin is called routine antenatal anti-D prophylaxis, or RAADP (prophylaxis means a step taken to prevent something from happening).
Routine antenatal anti-D prophylaxis
There are currently two ways that you can receive routine antenatal anti-D prophylaxis (RAADP):
- a one-dose treatment: where you will receive an injection of immunoglobulin in your shoulder at some point during weeks 28 to 30 of your pregnancy
- a two-dose treatment: where you will receive two injections into your shoulder; one during the 28th week and the other during the 34th week of your pregnancy
There does not seem to be any difference in terms of the clinical effectiveness between the one-dose or two-dose treatments. Your primary care trust (PCT) may prefer to use a one-dose treatment because it can be more efficient in terms of resources and time.
When will RAADP be given?
RAADP is recommended for all RhD-negative women who have not been sensitised to the RhD antigen. If you are RhD negative and routine tests carried out during your pregnancy show that sensitisation has not occurred, you will be offered RAADP. RAADP will not work if you’ve already been sensitised; instead you will be closely monitored and have regular blood tests and ultrasound scans.
Read more about how rhesus disease is diagnosed.
If rhesus disease starts to develop it will be treated either in the foetus or after birth, depending on when it is diagnosed.
Read more about how rhesus disease is treated.
Anti-D immunoglobulin after birth
After giving birth, a sample of your baby's blood will be taken from the umbilical cord. If your baby is RhD positive and you have not already been sensitised, you will be offered an injection of anti-D immunoglobulin within 72 hours of giving birth.
The injection will destroy any RhD-positive blood cells that may have crossed over into your bloodstream during the delivery. This will prevent sensitisation because your blood will not have a chance to produce antibodies. This will significantly decreasing the risk of your next baby having rhesus disease.
Complications from anti-D immunoglobulin
Some women are known to develop a slight short-term allergic reaction to anti-D immunoglobulin, which can include a rash or flu-like symptoms.
Although the anti-D immunoglobulin taken from the donor blood will be carefully screened, there is a small risk that an infection could be transferred through the blood. However, the evidence in support of RAADP shows that the benefits of preventing sensitisation far outweigh these small risks.
