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Fetal RhD genotyping


With the SensiGene Fetal RHD Genotyping test, you can find out from a simple blood draw whether your baby is RHD positive or negative. Testing can be performed anytime after 10 weeks' gestation.


What is Rhesus D?

Rhesus D (RhD) proteins are found on red blood cells. Many people know their blood type as a letter (A, B, AB or O) and either “positive” or “negative.” If your blood type is positive, it means that you have RhD proteins on your red blood cells. If your blood type is negative, it means that you do not have RhD proteins on your blood cells. Your chance of being RhD positive varies by ethnicity. About 85% of Caucasians are RhD positive, while 92-98% of African Americans and Hispanics and 98-99% of Asians and Native Americans are RhD positive.


What is RhD incompatibility?

RhD incompatibility in pregnancy occurs when you are negative for the Rhesus D factor and your unborn baby is positive. There is a risk that during pregnancy your unborn baby’s blood cells might enter your bloodstream. This causes an immune response in you and your body starts to make antibodies. These antibodies can destroy your unborn baby’s red blood cells and cause anemia to develop in the baby.

Normally, this doesn’t happen in the first pregnancy. However, you can become sensitized during birth, and develop antibodies that could cause RhD incompatibility in your future pregnancies.


What is RhD disease?

RhD disease in an unborn baby can result in jaundice, anemia, brain damage, heart failure or even fetal death. Without treatment, severe cases may result in pregnancy loss or stillbirth.


What is RHD Genotyping?

The SensiGene® Fetal RHD Genotyping test requires only a simple blood sample so it is safe for you and your baby. It's also highly accurate in detecting RHD, so you can trust the results. Testing can be performed any time after 10 weeks’ gestation, so you can know results as early as your first trimester. Your health care provider can use these results to decide if your pregnancy is at risk for RhD incompatibility. If needed, your health care provider can discuss options to prevent this problem, or monitor and treat your pregnancy if this condition develops.  


What treatment is available?

If you are RhD negative and your unborn baby is RhD positive, your health care provider may give you two Rh immune-globulin (Rhogam) shots, one at 28 weeks’ gestation and a second within 72 hours after birth. These shots help to prevent you from developing the damaging RhD antibodies if you are carrying a baby who is RhD positive.


No test is perfect:

While results of the SensiGene Fetal RHD Genotyping test are highly accurate, false positive and false negative results may occur in rare cases. A negative result does not ensure RhD compatibility. The results of this testing, including the benefits and limitations, should be discussed with your health care provider. 

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