Rhesus incompatibility

Synonyms

Blood group incompatibility

Introduction

Rhesus incompatibility (Rhesus- Incompatibility, Rh- Incompatibility) is an incompatibility between maternal and fetal blood. Typical for the occurrence of an incompatibility reaction is a Rhesus negative mother giving birth to a Rhesus positive child. This incompatibility can lead to hemolysis of the fetal erythrocytes and, in the worst case, to the development of haemolyticus neonatorum disease.

Before the introduction of anti-D prophylaxis for rhesus negative mothers, about 0.5% of all newborns developed rhesus incompatibility. Since the introduction of prophylaxis, the disease has become significantly rarer. During pregnancy, no fetal blood normally passes to the mother’s blood.

Thus the first child is usually born healthy. However, the blood of mother and child mixes during birth. If the mother is rhesus negative and the child rhesus positive, antibodies are formed on the mother’s side and rhesus incompatibility follows.

These antibodies can pass through the placenta and are therefore able to pass on to the child in the event of another pregnancy. This leads to the binding of the antibodies to the fetal erythrocytes and leads to the destruction of the blood cells. As a result, symptoms and clinical pictures of varying degrees of rhesus incompatibility may occur.

Such a course can also occur in the case of abortion, termination of pregnancy or amniocentesis, since maternal and fetal blood can also be mixed in these cases. Accordingly, the first child born alive can also be damaged. Depending on the degree of severity, three different forms of rhesus incompatibility can be distinguished, some of which are interrelated.

  • Anaemia neonatorum: In this form of rhesus incompatibility children often show extreme paleness. However, this can also be a symptom of other diseases and is therefore not a direct indicator of rhesus incompatibility. In addition, the extreme blood formation to compensate for the anemia results in a significantly enlarged liver and spleen (hepatosplenomegaly).
  • Icterus praecox and gravis: This leads to significantly elevated bilirubin levels, which causes the infant to turn yellow.

    This is caused by the loss of the numerous erythrocytes, which are destroyed by the maternal antibodies. When they are broken down, bilirubin is produced which can no longer be broken down in the infant’s organism. In the worst case, this can lead to the development of a nuclear icterus.

    In this case, the bilirubin crosses the blood-brain barrier and can irreversibly damage the child’s brain. The children can die from such an icterus or suffer lifelong severe neurological damage.

  • Hydrops congenitus universalis: This is the most severe form of rhesus incompatibility. This leads to massive edema accumulation in the entire child’s organism.

    The cause is severe anemia, which damages the tissue through an oxygen deficiency (hypoxia) and acidosis. In addition, there is a loss of protein and an increased permeability of the tissue. This leads to edema formation in the body cavities.

The diagnosis of rhesus intolerance should begin with prenatal care.

Rhesus negative mothers must be monitored more closely. An indirect Coombs test should also be performed. This test detects the corresponding placental antibodies in maternal serum.

In order to accurately assess the condition of the child, amniotic fluid must be taken repeatedly to check the bilirubin content. However, whether the fetus is suffering from anemia, or how advanced it is, can only be determined by means of a fetal blood analysis. This requires an umbilical cord puncture under ultrasound control.

Ultrasound can also detect edema, an enlarged liver and spleen and pleural effusions. All these would indicate a progression of the disease. The controls must be correspondingly close meshed.

This also applies after birth. Since bilirubin concentrations can increase rapidly after birth, it is important to control them at short intervals. The treatment of rhesus intolerance depends on the form of the disease.

The most important goal of treatment is to avoid a kernicterus and to treat anemia.If the child is already at vital risk before the 20th week of pregnancy, the only option is a blood transfusion via the umbilical cord or peritoneum. Excessive bilirubin levels after birth can be treated most effectively with the help of phototherapy. Phenobarbital can be given as a support.

This supports the enzyme activity of the liver. If there is a very rapid increase in bilirubin (icterus praecox), an exchange transfusion should be carried out to avoid a nuclear icterus. Hydrops fetalis always represents an acute emergency for pediatricians and requires intensive medical treatment.

Usually the children are intubated directly in the delivery room, as they cannot breathe due to the effusions in their lungs. To relieve the pressure on the body cavities, the effusions are punctured and an exchange transfusion is always performed. Within 24 to 72 hours after the birth of the first child, the mother receives anti-D antibodies.

This eliminates the fetal erythrocytes and prevents sensitization in over 90% of cases. This significantly reduces the risk of rhesus incompatibility for a further pregnancy. Rhesus incompatibility can have very serious consequences and therefore requires very close monitoring during and after pregnancy.

In most cases, no invasive therapy is necessary to cure the child. A distinction is made between a mostly simple anemia, hyperbilirubinemia and hydrops congenitus fetalis. The latter is life-threatening and intensive care measures are necessary to save the child.

For this reason, children at risk should be born in the immediate vicinity of a perinatal center in order to be able to help directly in the event of serious problems. In order to avoid the occurrence of rhesus intolerance, affected mothers are nowadays injected with antibodies shortly after the birth of the first child, which in most cases prevents rhesus intolerance in a second pregnancy. Further interesting information from this topic area: An overview of all topics in gynecology can be found at Gynecology A-Z

  • Blood group incompatibility
  • Pregnancy complications
  • Preventive examination during pregnancy