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Rh(D) status of an individual is normally described with a positive (+) or negative (−) suffix after the ABO type (e.g., someone who is A+ has the A antigen and Rh(D) antigen, whereas someone who is A− has the A antigen but lacks the Rh(D) antigen). The terms Rh factor, Rh positive, and Rh negative refer to the Rh(D
The term "Rh Disease" is commonly used to refer to HDFN due to anti-D antibodies, and prior to the discovery of anti-Rh o (D) immune globulin, it was the most common type of HDFN. The disease ranges from mild to severe, and occurs in the second or subsequent pregnancies of Rh-D negative women when the biologic father is Rh-D positive.
Individuals with a positive RhD status have RhD antigens expressed on the cell membrane of their red blood cells, whereas Rhesus D antigens are absent for individuals with a negative RhD status. Rhesus factor testing is usually performed on pregnant women to determine the RhD blood group of the mother and the fetus.
A Rhc negative mother can become sensitised by red blood cell (RBC) Rhc antigens by her first pregnancy with a Rhc positive fetus. The mother can make IgG anti-Rhc antibodies, which are able to pass through the placenta and enter the fetal circulation. If the fetus is Rhc positive alloimmune hemolysis can occur leading to HDN.
Wiener's theory is that Rh inheritance is controlled as follows: There is one Rh locus at which occurs one Rh gene, but this gene has multiple alleles. For example, one gene R1 produces one agglutinogen (antigen) Rh1 which is composed of three "factors": rh', Rh(o), and hr' '. The three factors are analogous to C, D, and e respectively in the ...
Blood compatibility testing is routinely performed before a blood transfusion.The full compatibility testing process involves ABO and RhD (Rh factor) typing; screening for antibodies against other blood group systems; and crossmatching, which involves testing the recipient's blood plasma against the donor's red blood cells as a final check for incompatibility.
If a D-negative patient has developed anti-D antibodies, a subsequent exposure to D-positive blood would lead to a potentially dangerous transfusion reaction. Rh D-positive blood should never be given to D-negative women of child-bearing age or to patients with D antibodies, so blood banks must conserve Rh-negative blood for these patients.
These products are given to Rh(D) negative mothers of unknown or Rh(D) positive babies during and after pregnancy to prevent the creation of antibodies to the blood of the Rh(D) positive child. This antigen sensitization and subsequent incompatibility phenomenon causes Rhesus disease, the most common form of HDN. [4]