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The Rh Factor


Prevention and Treatment

Can Rh disease be prevented?

A simple blood test can reveal whether or not you have Rh-negative blood. Every woman should be tested early in pregnancy, or prior to pregnancy, to find out. To prevent Rh disease, an Rh-negative woman should receive an injection of Rh immunoglobulin (RhIg) within 72 hours of delivering an Rh-positive baby. This prevents sensitization in more than 95 percent of Rh-negative women. However, studies show that about 2 percent of pregnant women become sensitized prior to delivery. For this reason, an RhIg injection is given around the 28th week of pregnancy as well.

The RhIg treatment must be repeated with each pregnancy, miscarriage, abortion, and blood transfusion with Rh-positive blood, and after amniocentesis (a procedure in which a needle is inserted into the uterus to obtain a small sample of amniotic fluid) or another prenatal test called chorionic villus sampling (CVS).

Unfortunately, RhIg will not work for an Rh-negative woman who has already been sensitized (her body has produced antibodies to Rh-positive cells) by a prior pregnancy, miscarriage, abortion, or transfusion.

What's the treatment for Rh disease?

If your unborn baby is Rh-positive, your doctor will need to measure the levels of antibodies in your blood as pregnancy progresses. If high levels of antibodies are found, tests will be given to help determine whether the baby is developing anemia (a sign of Rh disease) and if so, how severe it may be. These tests may include amniocentesis and another procedure called cordocentesis, in which the doctor, guided by ultrasound, inserts a thin needle through the mother's abdomen into the umbilical cord to take a blood sample.

Based on test results, a doctor may advise inducing labor early, before the mother's antibodies destroy too many fetal blood cells. Or he may treat the fetus with a blood transfusion, usually using cordocentesis, as early as the 18th week of pregnancy.

After delivery, if the baby has jaundice, she may be given phototherapy — placed under special blue lights. If jaundice does not respond to phototherapy, or if the baby is anemic, a blood transfusion may be necessary. But some cases of Rh disease are so mild that they require no treatment.

With widespread use of RhIg, few women today need to be concerned about Rh disease. You can protect your baby by learning your Rh status and, if you are Rh-negative, following your doctor's advice.


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