This is a matter of utmost importance to a great majority of people across the world. In many cases, the availability of blood of the appropriate type is a matter of life and death. This stark reality presents the average doctor with a serious dilemma many times in his practising career.
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Blood has been described in many ways by many people, but perhaps the most enduring of these descriptions is the one that recognises blood as ‘the juice of life.’ Others describe it as life itself. As a result, the average doctor is confronted in nearly all the specialties of medical practice with the daily challenge of deciding who should be taking a blood transfusion and those who should not. That decision is not based on conjecture; it is the product of rigorous laboratory analysis grounded on years of research. That decision is based on the existence of the major blood groups which were described early in the 20th century by a dedicated team of workers determined to end the nightmare of enduring high death rates from routine operations as we know them to be today. The most prominent of these dedicated men and women is Karl Landsteiner.
Many other people would have had no chance in the world of living as long as they have done without the science and practice of blood transfusion. Without a doubt, it has saved millions of people and has reduced the stress of modern medical practice. All the blood types are made up of the same basic elements called antigens which have proteins that determine the peculiar character of each one. Not all blood types are consequently alike and the presence or absence of those antigens – the protein substances which determine whether a blood type would react favourably or adversely to exposure to another blood type – is the very foundation of the practice of routine blood transfusion. Since some of these antigens are responsible for setting off the chain of events that make it possible for a patient’s blood to attack transfused blood, safe blood transfusions depend on care blood grouping and cross-matching.
There are four major blood groups which are determined by the presence or absence of the two main antigens which exist on the surface of the red blood cells. These antigens are known as the –A and the –B antigens. It is known as the ABO system. Ultimately, our blood groups are inherited. They are passed on from our parents. Whether the resulting blood group is A, B, AB or O depends on the blood groups of one’s mother or one’s father. According to the American Red Cross, the various blood groups are largely as depicted below.
Group A - This has only the A antigen on the red blood cells. It thus has the opposite B antibody in the plasma. The plasma is the liquid in which the red blood cells flow. These people can donate blood to Group A and Group AB.
Group B - In contrast to Group A, this group has the B antigen on the surface of their red blood cells. This means that people who have Group B blood type also have the A antibody in their plasma. They can thus donate blood to Group B and Group AB.
Group AB - This is a unique blood group which has both the A and B antigens on the surface of the red blood cells, but neither the A nor the B antibody in their plasma. As a result, they can only donate blood to other ABs but can receive blood from all others. This is a selfish blood group in that sense.
Group O – This group does not have either the A or the B antigen on its red blood cells. Both these antibody groups exist in the plasma. The absence of those antigens on the red blood cells enables these people to donate blood to any blood group; hence, the common appellation of being the universal donor. This is also the most common blood group among Black people. There is no best or worst blood group.
In addition to the above A and B antigens, there is a third antigen known as the Rh factor. That factor can either be present, in a group called positive (+) or absent and called negative (-). Most Black people have the Rh (+) factor in about 95 per cent of cases, with the rest being Rh (-). This is a blood type first seen in the Rhesus monkey. Generally speaking, Rh negative blood is given only to Rh negative patients while Rh positive blood can be given to both groups. Thus, the true universal red blood cell donor is O-negative while the universal donor of plasma is AB positive.
It is a healthy practice to donate blood. If you are in the age bracket of 16 to 65, you can donate blood. This also applies to women as long as they have not recently delivered a baby or had a major operation. A blood donor must be fit, and should not be an individual recently recovering from diseases like malaria. They also should not be people with the HIV virus or the Hepatitis B or C. These different organisms are usually tested for at the point of blood donation. It is not a random practice. Fit individuals can donate blood every three months; for the women in the reproductive age, twice a year. Sadly, it is a practice that is still largely viewed with suspicion by many Nigerians.
- DR. SYLVESTER IKHISEMOJIE/PUNCH
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