This is the abnormal breakup of red blood cells in the fetus or newborn. This is usually due to antibodies made by the mother directed against the baby’s red cells. It is typically caused by Rh incompatibility that is, differences between the Rh blood group of the mother and baby. Severe hemolytic disease can cause anemia and heart failure. Less severe cases include Jaundice and can lead to brain damage if left untreated.
HDN most frequently occurs when an Rh negative mother has a baby with an Rh positive father. When the baby’s Rh factor is positive, like the father’s, problems can develop if the baby’s red blood cells cross to the Rh negative mother. This usually happens at delivery when the placenta detaches. However, it may also happen anytime blood cells of the two circulations mix, such as during a miscarriage or abortion, with a fall, or during an invasive prenatal testing procedure (such as an amniocentesis or chorionic villus sampling).
The mother’s immune system sees the baby’s Rh positive red blood cells as “foreign.” Just as when bacteria invade the body, the immune system responds by developing antibodies to fight and destroy these foreign cells. The mother’s immune system then keeps the antibodies in case the foreign cells appear again, even in a future pregnancy. The mother is now Rh sensitized.
In a first pregnancy, Rh sensitization is not likely. Usually, it only becomes a problem in a future pregnancy with another Rh positive baby. During that pregnancy, the mother’s antibodies cross the placenta to fight the Rh positive cells in the baby’s body. As the antibodies destroy the red blood cells, the baby can become sick. This is called erythroblastosis fetalis during pregnancy. In the newborn, the condition is called hemolytic disease of the newborn.
Symptoms During Pregnancy
- With amniocentesis, the amniotic fluid may have a yellow coloring and contain bilirubin.
- Ultrasound of the fetus shows enlarged liver, spleen, or heart and fluid buildup in the fetus’s abdomen, around the lungs, or in the scalp.
After Birth symptoms
- A pale coloring may be evident, due to anemia.
- The newborn may have an enlarged liver and spleen.
- Babies with hydrops fetalis have severe edema (swelling) of the entire body and are extremely pale. They often have difficulty breathing.
- Testing for the presence of Rh positive antibodies in the mother’s blood
- Ultrasound – To detect organ enlargement or fluid buildup in the fetus.
- Amniocentesis – To measure the amount of bilirubin in the amniotic fluid. Amniocentesis is a test performed to determine chromosomal and genetic disorders and certain birth defects. The test involves inserting a needle through the abdominal and uterine wall into the amniotic sac to retrieve a sample of amniotic fluid.
- Sampling of some of the blood from the fetal umbilical cord during pregnancy to check for antibodies, bilirubin, and anemia in the fetus.
Diagnostic Tests after Birth
- Testing of the baby’s umbilical cord blood for blood group, Rh factor, red blood cell count, and antibodies
- Testing of the baby’s blood for bilirubin levels
Fortunately, HDN is a very preventable disease. Because of the advances in prenatal care, nearly all women with Rh negative blood are identified in early pregnancy by blood testing. If a mother is Rh negative and has not been sensitized, she is usually given a drug called Rh immunoglobulin (RhIg), also known as RhoGAM. This is a specially developed blood product that can prevent an Rh negative mother’s antibodies from being able to react to Rh positive cells. Many women are given RhoGAM around the 28th week of pregnancy. After the baby is born, a woman should receive a second dose of the drug within 72 hours, if her baby is Rh positive. If her baby is Rh negative, she does not need another dose.
Infants with HDN may be treated with:
- Feeding often and receiving extra fluids
- Light therapy (Photo-therapy)using special blue lights to convert bilirubin into a form in which the baby’s body can get rid of it
- Antibodies (intravenous immunoglobulin, or IVIG) to help protect the baby’s red cells from being destroyed
- Medicines to raise blood pressure if it drops too low
- In severe cases, an exchange transfusion may need to be performed. This involves removing a large amount of the baby’s blood, and thus the extra bilirubin and antibodies. Fresh donor blood is infused.
Complications of HDN could include kernicterus, hepatosplenomegaly, greenish staining of the teeth, hemolytic anemia and damage to the liver due to excess bilirubin. Similar conditions include acquired hemolytic anemia, congenital toxoplasma and syphilis infection, congenital obstruction of the bile duct and cytomegalovirus infection.
- High at birth or rapidly rising bilirubin
- Prolonged hyper-bilirubinemia
- Bilirubin Induced Neurological Dysfunction
- Cerebral Palsy
- Hemolytic Anemia – MUST NOT be treated with iron
- Late onset anemia – Must NOT be treated with iron. Can persist up to 12 weeks after birth.
Once a woman has antibodies, she is at high risk for a transfusion reaction. For this reason, she must carry a medical alert card at all times and inform all doctors of her antibody status.
Acute hemolytic transfusion reactions may be either immune-mediated or non-immune-mediated. Immune-mediated hemolytic transfusion reactions typically result in severe, potentially fatal complement-mediated intravascular hemolysis. Immune-mediated hemolytic reactions typically result in extra vascular sequestration, shortened survival of transfused red cells, and relatively mild clinical reactions. Acute hemolytic transfusion reactions due to immune hemolysis may occur in patients who have no antibodies detectable by routine laboratory procedures.