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Know your Rhesus factor

By Dr Rotimi Adesanya
~Punch Nigeria. WEDNESDAY, SEPTEMBER 5, 2018.
Dr Rotimi Adesanya

About 95 per cent of Nigerians are Rhesus Disease positive. The remaining five per cent are RhD
negative. There is a need to encourage parents, especially mothers, to know their blood groups and Rhesus factors because it could help to reduce or prevent cases of mortality.

I have on several occasions seen patients request information on their blood groups. Not one person ever mentioned his Rhesus factor as the reason making the request.

A popular Chinese proverb says "The beginning of health is to know the disease". This explains why it is important for everybody to be aware of this condition.

There are several different types of human blood. The four main blood groups are:

blood group A
blood group B
blood group AB
blood group O
Each of these blood groups can either be RhD positive or RhD negative. The RhD is a protein that is either present or absent on the surface of the red blood cells. This is indicated by a plus sign + or a minus sign -. The blood type O+ means that the blood is type O and each blood cell has RhD positive.

A simple blood test can tell if a woman is RhD negative. Every woman should be tested at her first prenatal visit, or before pregnancy, to find out if she is Rh-negative. The RhD negative gene is recessive, while the RhD positive gene is dominant. This means that there is a chance that a woman who is RhD negative will give birth to a RhD positive child.

A person who is RhD negative may have an immune reaction if RhD positive blood cells enter his bloodstream. A pregnant woman's body considers the RhD positive cells a threat and it mounts an immune system response. Her immune system makes antibodies, also known as anti-RhD antibodies, against the cells. If the woman conceives another RhD-positive baby, her anti-D antibodies will attack her unborn baby's red blood cells. Such complication is also known as the Haemolytic disease of the newborn.

The Rhesus disease destroys foetal red blood cells. It was once considered to be a leading cause of foetal and newborn deaths. Without treatment, severely affected foetuses are often stillborn.



In the newborn, Rh disease can result in jaundice (yellowing of the skin and eyes), anaemia, brain damage, heart failure and death. It can also affect the mother's mental state. Most mothers are always depressed after such a loss.

In the past, most of the foetal deaths resulting from this disease were interpreted in the rural society as caused by Abiku or Ogbanje spirits. In some instances, they were associated with witchcraft.

Most times, the Rhesus disease does not manifest any symptom and it can cause recurrent still-birth, jaundice and mental retardation in infants.

Prevention of Haemolytic disease of the newborn

Prevention is the best form of treatment. An anti-HDN has been available for many years. The vaccine helps to prevent the mother's immune system from making antibodies. It also protects future pregnancies from the Rhesus disease.

Studies indicate that about 99 per cent of RhD negative mothers do not make antibodies after receiving the vaccine, which contains anti-RhD immunoglobulin and intramuscular injection of anti-RhD antibodies, is given as an injection to the RhD negative mother during pregnancy and after she gives birth to an RhD positive baby.

RhD negative women should also be vaccinated, if there is a possibility of fetal blood entering their bloodstream, for example, after marriage, abortion, amniocentesis, abdominal trauma during pregnancy or after manipulation of a breech presentation during labour.

A mother, who is RhD positive, does not need the vaccine because her pregnancy carries no risk of Rhesus incompatibility.

Treatment of HDN

Treatment is complex and the preferred medical treatment for a baby born with HDN is blood transfusion. The baby's damaged blood is regularly replaced in small amounts with compatible donor blood. The blood exchange continues until the baby's blood has been completely replaced with healthy donor blood. The transfusion also removes maternal anti-D antibodies, which prevent damage to the baby's new red blood cells.

Unfortunately, most young ladies who may have been exposed to abortion may also have been sensitised without knowing it, especially if the aborted foetus was RhD positive. Such a woman does not need an injection after delivery if her baby is Rh-negative.

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