What is Rhesus incompatibility?

Everything you need to know about rhesus incompatibility

How to screen for the risk factors of Rhesus incompatibility?

During the first trimester of pregnancy, we are tested for blood group and Rhesus factor. Why ? If this research reveals that one is Rh negative, the same research should be done for the dad. In the event that it is Rh positive, blood incompatibility may occur during pregnancy.

When is Rhesus incompatibility a problem?

If both the Rh negative woman and the Rh positive man have an Rh negative child, there is no problem. On the other hand, if the child is Rh positive, there is a risk of fetal-maternal incompatibility. Why ? The red blood cells (Rhesus positive) of the fetus can (this is not automatic) pass into the mother’s body which will react by making anti-Rhesus antibodies (or agglutinins). These agglutinins can also pass through the placenta and destroy red blood cells in the fetus, which can be more or less serious for the fetus. Fortunately, the risk is almost zero during a first pregnancy. Indeed, it is generally at the time of childbirth and delivery that the red blood cells of the fetus are in contact with the blood of the mother. The antibodies developed by the mother are therefore no longer dangerous for the newborn. However, they can be for subsequent pregnancies (always if the children are Rh +), if the agglutinins remain in the woman’s blood, a rare case today.

How can the red blood cells of the fetus pass into the maternal blood?

Normally, there is no contact between the blood of the fetus and that of the mother during pregnancy. However, during amniocentesis, miscarriage, placental abruption, ectopic pregnancy, shock to the stomach, there may be contact. Generally, it is during childbirth that the blood mixes.

What are the risks for the fetus?

In the worst case, extremely rare today, the fetus can be affected by severe anemia. Treatment may consist of replacing the blood of the fetus. An in utero transfusion is then performed. This procedure corrects the anemia over ten days and must be repeated until birth. If anemia begins after birth, it is very often accompanied by neonatal jaundice (jaundice).

Why is Rhesus incompatibility rare today?

Prevention is such that serious situations are almost non-existent. When it is established that one is Rh – and that our companion is Rh +, the monitoring of the pregnancy is increased. Each month, a research and a dosage of agglutinins are made. In addition, an anti-Rhesus vaccination is given at 28 weeks in all Rh – women who are with an Rh + man. Finally, within 72 hours after childbirth, the mother is injected with antibodies (gammaglobulins) to destroy the Rhesus positive red blood cells, before she has had time to make agglutinins. Note that a test to determine the Rhesus group of the fetus has been put into circulation. Its advantage: if we discover that the fetus is Rh -, the mother will not have to receive anti-Rhesus vaccination.

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