Rhesus factor (Rh factor) is an inherited protein found on the surface of red blood cells. If your red blood cells have an Rh factor then you are Rh positive and if you do not have Rh factor on the red blood cells then you are Rh negative. Being Rh negative does not affect your health. It may affect your pregnancy and special care should be taken. Rh factor is inherited to the baby from either of the parents.
How Rh antibodies are formed?
Blood groups are classified according to the presence or absence of Rh antigen usually called as Rh factor on the red blood cells. The Rh term is derived from the rhesus monkey as monkey’s blood is used for the tests. The Rh antibodies will be developed if an individual who does not have Rh factor on his/her red blood cells or an Rh-negative individual is exposed to Rh-positive red blood cells. This usually happens in pregnancy and during childbirth when an Rh-negative woman gets pregnant with an Rh-positive baby or when an Rh-negative person is transfused with Rh-positive blood. In both the cases, the exposure to the Rh antigen may not lead to any responses against the Rh positive cells but the next exposure may lead to serious reactions.
Why this test is performed?
This test may be recommended during the blood transfusion or if you are donating the blood. Blood transfusion may be necessary in cases like severe blood loss, heavy bleeding, bleeding during or after surgery, bleeding disorders such as hemophilia, severe anemia, injury, trauma, etc. This is also recommended in pregnancy to know if the mother is Rh positive or Rh negative. This test is also recommended if you are planning to get pregnant or if you are Rh negative and got pregnant with an Rh positive man.
Rh factor test is very important in pregnancy. If the mother is Rh negative and the baby is Rh positive, then there is an Rh incompatibility. In pregnancy, there may be cases where a baby’s blood passing into mother’s body through the placenta. Then the body may consider the baby’s blood as a foreign substance and produces antibodies against it. This condition may lead to a miscarriage, problems with later pregnancy, anemia, bleeding during pregnancy, the fetus develop outside the uterus mostly in the fallopian tube (ectopic pregnancy), change in position of the baby, non-cancerous tumor in uterus, abdominal trauma, etc. Generally, Rh incompatibility is not a problem in the first pregnancy because most of the antibodies are not produced before the childbirth and do affect the childbirth. But during the second pregnancy with an Rh-positive baby may lead to life-threatening anemia.
Inform your doctor if you are on any medications, have any allergies or underlying medical conditions before your RA Factor Test. Your doctor will give specific instructions depending on your condition on how to prepare for RA Factor Test.
No specific preparation is needed for Rh factor blood test.
If your test results show positive, it means Rh factor is present in your blood.
If your test results are negative, it means Rh factor is absent in your blood. If your test results show Rh negative then an antibody screen test is recommended.
This test helps in knowing about the antibodies in the body. If antibodies are present in your blood, it shows that Rh-positive blood has come in contact with your blood and produced antibodies against it. Multiple antibody screen tests may be necessary during pregnancy and once at the time of childbirth.
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