What is the rhesus factor in the blood group system?

Blood types can not only be differentiated into A, B, AB, or O according to the ABO system, but also through the Rhesus (Rh) factor system. This component is checked in a blood group check. The Rh factor is seen in the presence of a built-in protein in your red blood cells. Consider the following review to understand the Rhesus (Rh) system in more detail.

What is the Rhesus (Rh) factor?

Rhesus factor (Rh) is a type of protein found outside of red blood cells. This protein is inherited genetically or passed down from your parents.

As you know, every human being has a different blood type, namely A, B, O, or AB. Each blood group is again differentiated based on its Rhesus (Rh) protein content.

Based on the Rhesus (Rh) factor, blood types can be divided into:

• If it contains the Rh factor, your blood type is classified as Rhesus positive (Rh +), usually marked with a (+) symbol behind your blood type (example: A +, B +, AB +, O +).
• If it doesn't contain Rh protein, your blood type is classified as rhesus negative (Rh-), usually marked with a (-) symbol behind your blood group (examples: A-, B-, AB-, and O-).

Rhesus protein is something you get from heredity. Here are some possible factors about your Rh group:

• If your father has Rh + and your mother also has Rh +, you will get Rh +
• If your father has Rh + and your mother has Rh-, you have two possibilities. It could be that you, like your father, have Rh +, or you, like your mother, have Rh-
• If your father has Rh- and your mother also has Rh-, you will get Rh-

Any blood type that is Rh positive can receive a blood transfusion of the same blood type as Rh positive or negative. Meanwhile, those with negative blood type are Rhesus can only get blood donors of the same blood type or blood group O-.

Blood type O - can be a donor for all blood types. That is why this blood group is called the universal donor. Blood type O- is also the universal blood type needed for emergency transfusions and for immunocompromised infants.

What types of Rhesus are common in Indonesian society?

Quoted from the Cleveland Clinic, only a small proportion of the world's population (about 15%) have Rh-. Meanwhile, the other 85% are Rhesus positive.

The Red Cross Blood website states that there are only 0.2-1% of owners of negative Rhesus blood types in Asia. This means that Indonesia is one of the countries whose people are dominated by positive Rhesus blood types.

When is a blood test for Rh factor needed?

The Rhesus (Rh) factor can be determined by checking your blood type. In fact, the Rh factor has no direct impact on health. However, it is very important to know your rhesus if you are pregnant.

If you do not know your Rh factor, you may be advised to do this test before becoming pregnant (prenatal test). Especially if you are planning a pregnancy.

An Rh negative mother who is carrying a rhesus positive baby is at risk for health problems that will befall your child, especially in the second pregnancy and beyond. If your blood test shows a positive Rh factor, no follow-up needs to be done. It's different when the Rh result says you don't have it, aka negative.

Rh factor test results

In the early stages of the womb, pregnancy problems can arise if you are Rhesus negative, while the baby you are carrying is positive. This condition is known as rhesus incompatibility.

Usually, your blood does not mix with your baby's blood during pregnancy. However, a small amount of your baby's blood can come into contact with yours during labor or if you have bleeding. The meeting of your different rhesus blood with the child in the womb can also occur if there is abdominal trauma during pregnancy.

In conditions of Rhesus incompatibility, your body may produce proteins called Rh antibodies after exposure to the red blood cells of babies that are different from Rhesus. These antibodies may not be a problem during the first pregnancy. However, this condition could have a negative impact on future pregnancies.

If your next baby comes back Rh positive, these antibodies can cross the placenta and damage the baby's red blood cells. This condition can lead to life-threatening anemia, a condition in which the red cells are destroyed more quickly than they are replaced by the baby's body.

If it is Rh-, you may need to have another blood test, which is an antibody check, during the first trimester, during the 28th week of pregnancy, and at delivery. If your body hasn't started producing Rh antibodies, you may need an injection of a blood product called Rh immunoglobulin.

Meanwhile, if your baby was born Rh negative, there is no need for any follow-up actions. However, if your baby is born Rh positive, you will need more injections, immediately after delivery.

If your body is already producing Rh antibodies, an injection of Rh immunoglobulin will not help your condition. In this case, your baby will be closely monitored and may be given a blood transfusion via the umbilical cord if necessary.