An adult human has about 4-6 litres of blood that circulates in the body. It helps to circulate/transport oxygen to various parts of the body. Blood consists of several cells floating in a fluid called plasma, these cells are red blood cells which transports oxygen and remove carbon dioxide from the body tissues, white blood cells, that fights against infection while platelets helps to clot the blood.
Human blood is grouped into four types A, B, AB and O. The difference in the blood is due to the presence or absence of certain protein molecules called antigens and antibodies. Each letter refers to its antigen present on the surface of red blood cells. As blood group A, B and AB have A, B and A and B antigen respectively while in O no antigen is present. The antigens are present on the surface of red blood cells, while antibodies are in plasma. Presently more than 20 genetically determined blood group systems are known today, but AB and Rh system are most important for the blood transfusion purpose. It was Karl Landsteiner who discovered the ABO blood group system and he was awarded with the Nobel Prize in Physiology and Medicine in 1930.
Each blood group also possesses an additional factor i.e. called as Rhesus factor or Rh factor. This Rh factor was discovered in the blood of Rhesus monkey by Karl Landsteiner and Alexander S. Wiener in 1940. It was observed that when blood from Rhesus macaque monkey was injected into the rabbits and guinea pigs, it gets clotted. It was because of the presence of another antigen that was not classified before. Landsteiner and his co-workers called this antigen as Rh (Rhesus) factor. The symbol 'Rh' came from the first two letters of the species name of the monkey.
Most of the persons have this Rh factor on the red blood cells surface and called as Rh- positive (Rh+) those who does not have this factor called as Rh negative (Rh-). A person with Rh- does not have Rh antibodies naturally in the blood plasma. But a person with Rh- blood can develop Rh antibodies in the blood plasma if he or she receives blood from a person with Rh+ blood, whose antigens can trigger the production of Rh antibodies. A person with Rh+ blood can receive blood from a person with Rh- blood without any problems.
The discovery of Rh factor has a valuable practical importance, it is related with Rh- induced haemolytic disease of the new born or erythroblastosis fetalis. This condition is also called as Rh- incompatibility, or mother fetus incompatibility. Such status develops when the Rh- women married with Rh+ man, on pregnancy she has Rh+ fetus, this Rh+ factor may be inherited from father. If a woman get pregnant, during the prenatal visit to doctor she has been asked for the simple blood test to know wether she is Rh+ or Rh-. If she is Rh- and she does have Rh antibodies, the baby's father also will be tested to find out his Rh type. If he's Rh- too, the baby has no chance of having Rh+ blood. Thus, there's no risk of Rh incompatibility. If the baby's father is Rh+ the baby will have 50% or more chance of having Rh+ blood. As a result a woman is at high risk of development o Rh incompatibility.
In the womb fetus remains attached with the mothers body with the help of placenta, placenta is that organ that connects the fetus to the wall of uterus via umbilical cord. Nutrients and mother's antibodies regularly transfer across the placental boundary into fetus, but her red blood cells do not transfer until and unless there is accidental rupture.
In general anti Rh+ antibodies donot present in first case unless she had not previously came into the contact with Rh- blood. Placenta do ruptures normally at the normal child birth, so some fetal blood gets into mother's body, being Rh- the mother's immune system treats Rh+ fetal cells as these are foreign substances and makes antibodies against foetus blood cells. The first child is always normal because mother is exposed to Rh antigen during child birth when the damage of small blood vessels takes place and blood gets frequently exchanged between foetus and mother during child birth and it takes time for the mother to develop antibodies, first infant are not often get affected unless the mother has history of miscarriages that sensitized her immune system.
When the second pregnancy happens maternal antibodies cross the placenta and destroy fetal red blood cells as those get burst or agglutinate. When the red blood cells are broken down they make bilirubin. This causes jaundice to infant because of lack of oxygen. The infant may have large number of symptoms before birth which may include fast heart rate, enlarged heart, liver and spleen and swelling on the whole body. After birth baby suffers from anaemia a chronic blood condition because of low red blood cell count characterized by lack of energy, this cause the infant to be pale. Jaundice in which bile pigments build up in the blood and cause skin, eyeballs and urine to take on a yellow tone, this may be present at birth or appears within 24 hours after the birth. Small red or brown spots or purple patches on the skin also appear. Swelling on the whole body occur. This condition is called as erythrobastosis fetalis or haemolytic disease of new born or Rh incompatibility or mother fetus incompatibility.
Before birth this condition can be treated by blood transfusion, the unborn baby may need to have blood transfusion while still in the womb. In few cases the baby may need to be born earlier. After the birth the infant may have phototherapy in which bright lights are used to help break down of the bilirubin in infant's body. As the level of bilirubin decreases, the skin will lose its yellow color. In mild cases of haemolytic anaemia, few medicines may be given to prompt the body to make red blood cells. If the anemia persists at severe stage blood transfusion through umbilical cord may be done. The new born who has this condition will be treated with blood exchange transfusion which involves slow removal of the blood from new born and replacing it with fresh blood or plasma from a donor.
It can also be treated by immunizing Rh- woman for first and subsequent pregnancy with a serum Rho-GAM. The injected antibodies quickly agglutinate any fetal red cells as they enter the mother's blood by preventing her from forming her own antibodies. This is quite effective treatment for the prevention of this condition, without the use of Rho-GAM an Rh- woman will produce large amount of
Rh- antibodies in subsequent pregnancies and the risk of this disease will increase.
The erythroblastosis fetalis can be prevented by screening tests, if a lady is concerned about having problems, get her ABO and Rh blood types checked before getting pregnant. Otherwise, it may be done as a part of her first prenatal visit. If she has been pregnant before or had blood transfusions, she may need few additional tests. Rh factor treatments are the other best alternative, if the mother and her baby have an Rh type mismatch, she may be given Rh factor immune globulin. This medicine is given to prevent Rh incompatibility from happening. So the prerequisite is to be aware about the erythroblastosis fetalis signs and symptoms and to take the preventions at the right stage.
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