Rh Factor





What is Rh Factor?

Other than antigen A and B there have the presence of another antigen in human RBC which they termed as 'Rh factor' (from Rhesus) because this was first discovered in the Rhesus monkey, which was discovered by Landsteiner and Weiner in the year 1940. So the terms 'universal donor' and 'universal recipient' no longer remained applicable. People possessing the Rh factor (antigen) are called Rh (+ve) whereas those lacking it are called Rh (-ve). Different the antibodies of ABO system, the Rh antibody does not occur naturally in human plasma i.e., normally this antibody is present neither in Rh (+ve) nor in Rh (-ve) persons. The Rh antibody is created in the plasma of Rh (-ve) persons only when it is exposed to Rh antigen. Thus, Rh antibody is called as an induced antibody.




What is the significance of Rh-factor?

Besides the ABO system of blood grouping, the Rh factor should also be taken into account prior to transfusion of blood. If Rh (+ve) blood is given to a Rh (-ve) patient, the Rh antibody will be developed in the recipient's plasma giving rise to a possibility of agglutination. Generally, the first transfusion may not be fatal but a subsequent transfusion of Rh (+ve) blood to such a Rh (-ve) patient (i.e., who has developed Rh antibody) is always associated with agglutination because the Rh antibody persists in plasma for a long time.
Detection of Rh grouping is very important in pregnant women. If a Rh (-ve) mother carries a Rh (+ve) foetus,when the father is Rh (+ve), Rh antigen of the foetus would immunize the mother's blood by.-developing Rh antibody in it. The maternal Rh antibody may cause agglutination of the foetal red cells. This in turn results in construction of dead or severely anemic child. This is known as hemolytic disease of newborn.



Precautions of blood transfusion after considering Rh factor

The following factors should be kept in mind as precautions of blood transfusion: -

Compatibility

The blood to be transfused to a patient must be compatible with the recipient's blood. So, before transfusion, the blood groups of the donor and the recipient should be carefully checked and matched.

Selection of donor

The donor whose blood is taken for transfusion should be free from infectious or serious diseases so that the recipient may not get infected.

Rate and volume of transfusion

Blood transfusion should be made very slowly (drop by drop) through drip. Large volume of blood should not be given at a time through intravenous injection because sudden excess load of blood on the recipient's heart may lead to heart failure.

Hazards of incompatible transfusion

Blood transfusion should be made very slowly through drip. Large volume of blood should not be given at a time through intravenous injection because sudden excess load of blood on the recipient's heart may lead to heart failure.

What are the hazards of incompatible transfusion?

i) In case of incompatible transfusion, at first there occurs agglutination and hemolysis due to reaction between the antibody of recipient's plasma and antigen of the donor's red cells.
ii) As a result of hemolysis, the recipient may develops jaundice which is called hemolytic jaundice.
iii) The hemoglobin released from the hemolyzed red cells into plasma is filtered in the kidney and excreted in urine, this is named as hemoglobinuria.
iv) The hemoglobin passing through the renal tubules form acid hematin compound which blocks the tubules and causes renal failure. As a result of this, urine formation is impaired and the toxic materials like urea etc., cannot be eliminated from the blood. This leads to uremia which may causes death.
So, Rh factor has the same importance like the A, B, O grouping in case of blood transfusion.



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