Belmont, Calif: Brooks/Cole 2004.This article has been fact checked by a Board Certified Pediatrician. Human physiology – from cells to systems. Anatomy and physiology – the unity of form and function. Immune globulin binds foetal RBC antigens so that they cannot stimulate the mother’s immune system to produce anti-D, hence preventing HDN. As a result, it is now common to give immune globulin at 28-32weeks gestation and at birth to any pregnancy involving a Rh- mother and a Rh+ father. A Rh- mother is at risk of having a Rh+ baby if the baby’s father is Rh+. HDN is relatively easy to prevent, while very difficult to treat. Agglutinated RBCs haemolyse (release their Hb), and the baby is born with a severe anaemia called haemolytic disease of the newborn (HDN), which may kill the infant or leave brain damaged. If she becomes pregnant again with a Rh+ foetus, her anti-D antibodies can pass through the placenta and agglutinate the foetal RBCs. However, she does begin to produce anti-D antibodies upon her first exposure to Rh+ foetal blood, although this does not occur instantaneously. The first pregnancy is generally uneventful since anti-D does not form right away, so that even if the mother is exposed to Rh+ foetal blood via miscarriage or placental tearing at the time of birth, there is no danger to her first Rh+ child. Implications of Rhesus blood groups during pregnancyĪ related condition can occur when a Rh- woman is pregnant with a Rh+ foetus. However, because the recipient will now start producing anti-D, a subsequent Rh+ transfusion could agglutinate the donor’s RBCs. Since anti-D does not form instantaneously, there is little danger in the first mismatched transfusion. If an Rh- receives an Rh+ transfusion, the recipient produces anti-D antibodies. They only form in Rh- individuals who are exposed to Rh+ blood. In contrast to the ABO group, anti-D antibodies that react against D antigens are not usually present in the blood under normal conditions. People with the Rh+ blood group have D antigens on the surface of their red blood cells, while Rh- individuals do not. Individuals either belong to the Rh-positive (Rh+) or Rh-negative (Rh-) Rhesus blood group. The Rhesus or Rh blood group is named after the rhesus monkeys in which they were first discovered. Therefore, a person with type A (anti-B) blood cannot receive B or AB blood, a person with type B (anti-A) blood cannot receive A or AB blood, and a person with type O (anti-A and ant-B) blood cannot receive A, B or AB blood.įind and instantly book your next health appointment with Healthengine This free Hb can block the kidney tubules and cause death from kidney failure within a day or so. In giving transfusions, it is very important that the donor’s RBCs not agglutinate as they enter the recipient’s bloodstream.įor example, if type B blood (with B antigens) were transfused into a type A recipient (with anti-B antibodies), the recipient’s anti-B antibodies would immediately agglutinate the donor’s RBCs, causing a transfusion reaction where the agglutinated RBCs block small vessels and release their haemoglobin (Hb) over the next few hours to days. Agglutination is the clumping of RBCs bound together by antibodies. Importance of ABO blood groups in transfusionsĪn antibody can attach to several RBCs at once and bind them together. The antibody that reacts against antigen B is called anti-B and is present in those who do not possess antigen B in their RBCs – people with type O or type A blood. The antibody that reacts against antigen A is called anti-A, and is found in the plasma of people who do not possess antigen A on their own RBCs – that is, people with type O or type B blood. Individuals with type AB blood have both A and B antigens, whereas people with type O blood have no antigens present (there is no antigen O). People with type A blood have the antigen A on the surface of their RBCs, while people with type B blood have the B antigen.
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