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Mothers who are Rh negative (A−, B−, AB−, or O− blood types) and have anti-D antibodies (found on the antibody screen) need to determine the fetus's Rh antigen. If the fetus is also Rh negative (A−, B−, AB−, or O− blood types) then the pregnancy can be managed like any other pregnancy.
The name rhesus factor (Rh) goes back to the use of erythrocytes extracted from the blood of rhesus monkeys for obtaining the first blood serum. The Rh blood group system is a human blood group system. It contains proteins on the surface of red blood cells. After the ABO blood group system, it is most likely to be involved in transfusion reactions.
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]
This test is run from cord blood. [3] In some cases, the direct Coombs will be negative but severe, even fatal HDN can occur. [29] An indirect Coombs needs to be run in cases of anti-C, [30] anti-c, [30] and anti-M. Anti-M also recommends antigen testing to rule out the presence of HDN. [22] Hgb – the infant's hemoglobin should be tested from ...
Blood is taken from the mother, and using PCR, can detect the K, C, c, D, and E alleles of fetal DNA. This blood test is non-invasive to the fetus and is an easy way of checking antigen status and risk of HDN. Testing has proven very accurate and is routinely done in the UK at the International Blood Group Reference Laboratory in Bristol. [21]
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.
It is estimated that less than 1ml of fetal blood is lost to the maternal circulation during normal labour in around 96% of normal deliveries. [1] [2] The loss of this small amount of blood may however be a sensitising event and stimulate antibody production to the foetal red blood cells, an example of which is Rhesus disease of the newborn.
The term human blood group systems is defined by the International Society of Blood Transfusion (ISBT) as systems in the human species where cell-surface antigens—in particular, those on blood cells—are "controlled at a single gene locus or by two or more very closely linked homologous genes with little or no observable recombination between them", [1] and include the common ABO and Rh ...