Tests that categorize your blood according to the major human blood group ABO system (O, A, B, AB). Rh Factor testing determines whether the configuration is rh-positive or rh-negative.
Why do patients need it?
This is generally done during your first prenatal visit because this can affect your pregnancy. Your pregnancy likely needs special care if you are Rh negative. A baby can inherit the Rh factor from either parent. This can also be done to determine compatibility for blood transfusions, and more.