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What is Rh Sensitisation during Pregnancy?
Rhesus or Rh factor is an antigen present on the red blood cells, which makes the blood group Rh positive. Individuals without the Rh factor are considered Rh negative. When Rh-negative blood mixes with Rh-positive, it results in a strong immune system reaction, that produces antibodies against this antigen. These antibodies may destroy the red blood cells, causing Rh sensitisation. If this condition happens during pregnancy to an Rh-negative mother whose baby is Rh positive, it is known as Rh sensitisation during pregnancy.
What are the main signs and symptoms?
During the first pregnancy, no reaction is usually triggered. If the first pregnancy goes beyond 40 weeks, it rarely results in the destruction of placenta (placenta abruptio) leading to profuse bleeding.
However, during the second pregnancy, if the baby is Rh positive again, the newborn suffers from jaundice, anaemia, or occasional death and spontaneous abortion (condition known as erythroblastocyst foetalis). This occurs because the mother’s body produces antibodies to the Rh-positive blood cells in the baby.
What are the main causes?
When the mother has an Rh-negative blood group and the developing foetus is Rh positive, during the first pregnancy, there is a mixing of baby’s and mother’s blood at birth, leading to exposure of the mother’s blood to the Rh antigen. However, during the second pregnancy, if this scenario repeats, the mother’s body already has antibodies against the Rh factor antigen and attacks the red blood cells of the foetus, leading to damage or spontaneous abortion.
How is it diagnosed and treated?
An adequate medical history along with the Rh status of the woman and her partner is evaluated. If the woman is Rh negative and her partner is Rh positive, Rh incompatibility tests are performed.
A direct Coombs test gives an idea about the presence of antibodies against the Rh factor in the mother’s blood. A positive Coombs test indicates Rh incompatibility.
Treatment for Rh incompatibility is usually given to the newborns, which is based on the severity of the blood loss. Mild blood loss may require re-evaluation in the last trimester or at the 28th week.
If anaemia (blood loss) is severe or worsens, early delivery may be required, and blood transfusion may be needed.
