How does Rh conflict arise?
Rh factor is a protein on the surface of red blood cells. A Rh-negative woman does not have it, and foreign Rh-positive red blood cells are perceived by the immune system as foreign. A small amount of fetal blood is sufficient to produce antibodies. This is called sensitization or alloimmunization. If sensitization has already occurred, it persists for life, and each subsequent pregnancy with an Rh-positive child may be more difficult.
- Giving birth to an Rh positive baby
- Abortion, miscarriage, ectopic pregnancy
- Bleeding during pregnancy
- Abdominal injury
- Amniocentesis and other invasive procedures
- Transfusion of incompatible blood
Who's at risk
Rh conflict is impossible if the mother has Rh positive blood. If both parents are Rh negative, the child will also be Rh negative, and the conflict does not develop. If the father's Rh is unknown or positive, the woman is observed as at risk. In some centers, the fetal Rh factor is determined by its DNA in the mother's blood, which avoids unnecessary prophylaxis.
- Mother is Rh negative, father is Rh positive
- Father's Rh is unknown
- Previous pregnancies without prophylaxis
- Identified anti-Rhesus antibodies
How dangerous it is for a child
The mother's antibodies destroy the fetus's red blood cells, and he develops anemia. The child's liver and spleen enlarge, trying to replenish blood loss. In severe cases, swelling occurs and fluid accumulates in the cavities—fetal hydrops, which is life-threatening. After birth, the destruction of red blood cells continues: jaundice increases rapidly, and high levels of bilirubin can damage the brain. Timely observation allows timely intervention.
- Fetal anemia
- Enlarged liver and spleen
- Hydrops fetalis
- Jaundice of the newborn
- Risk of bilirubin encephalopathy
Pregnancy examination
When registering, all pregnant women have their blood type and Rh factor determined. In Rh-negative women, anti-Rh antibodies are tested and the test is repeated during pregnancy. If there are no antibodies, prophylaxis is carried out. If antibodies are detected, observation is carried out in a specialized center: the antibody titer is regularly assessed and Doppler measurements of the fetal middle cerebral artery are performed. A high blood flow rate in it indicates fetal anemia.
- Blood type and Rh factor of mother and father
- Anti-Rhesus antibodies and their titer
- Doppler ultrasound of the fetal middle cerebral artery
- Ultrasound of the fetus for signs of edema
- Determination of fetal Rhesus by DNA in the mother's blood - if possible
Prevention and treatment
The main defense is anti-Rhesus immunoglobulin. It binds fetal red blood cells that have entered the mother's blood before the immune system has time to produce antibodies. For an Rh-negative woman without antibodies, it is administered at 28 weeks of pregnancy, within 72 hours after the birth of an Rh-positive baby, and after abortion, miscarriage, ectopic pregnancy, bleeding, abdominal trauma and invasive procedures. If the conflict has already developed, in case of severe fetal anemia, an intrauterine blood transfusion is performed and birth is planned ahead of schedule. The newborn may require phototherapy or exchange transfusion.
- Anti-Rhesus immunoglobulin at 28 weeks
- Repeated administration after delivery of an Rh-positive baby
- Prevention after abortion, miscarriage, bleeding
- Intrauterine blood transfusion for severe fetal anemia
- Phototherapy and exchange transfusion in the newborn
