Obstetrics and Gynecology

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Isoimmunization (Sometimes called Rh sensitization, hemolytic disease of the fetus, Rh incompatibility)

What is isoimmunization? 

A condition that happens when a pregnant woman's blood protein is incompatible with the baby's, causing her immune system to react and destroy the baby's blood cells.

What causes isoimmunization? 

When the proteins on the surface of the baby's red blood cells are different from the mother's protein, the mother's immune system produces antibodies that fight and destroy the baby's cells. Red cell destruction can make the baby anemic well before birth. Although the Rh(D) protein is the most common one, several other proteins can cause this problem, including among proteins KELL, Kidd, Duffy, and others.

What are the symptoms of isoimmunization?

The mother will not have symptoms from isoimmunization but for the baby symptoms can range from mild to dangerous. Even mild, the incompatibility causes destruction of the red blood cells without showing other effects. When the process is severe enough, the baby can become very anemic and, in some cases may die. After birth, the baby's skin and whites of the eyes will appear yellow (jaundice) and the baby will have low muscle tone (hypotonia) and lethargy.

How is isoimmunization diagnosed?

Women at risk for isoimmunization can be identified at prenatal visits with tests that measure blood type, Rh type and antibody screening. Occasionally the specific incompatibility is diagnosed before birth through amniocentesis. If isoimmunization is diagnosed, we monitor the severity of the baby's anemia utilizing ultrasound. After birth, there may also be a positive reading on a blood test called Coombs, higher-than-normal levels of bilirubin from blood samples from the baby's umbilical cord, and signs of red blood cell destruction in the infant's blood.

What is the treatment for isoimmunization?

If the baby's anemia is severe, one of the following two options are available. If the baby is mature enough to safely move to delivery, the baby is delivered and placed in the intensive care nursery for transfusions and other therapies under the direction of the neonatologists. If the baby is too premature to safely deliver, red blood cells are transfused to the baby before it is born by inserting a needle into the baby's umbilical cord and administering red blood cells.

How can isoimmunization be prevented?

Once identified as having Rh negative blood type, the pregnant and/or newly delivered mom can be given RhoGAM (Rh-immune globulin).