Blood type test – find out your blood type and RhD status
With a blood type test, you will find out which ABO blood type you have – A, B, AB or O – and whether you are RhD positive or RhD negative. The analysis also includes screening for irregular erythrocyte antibodies. Knowing your blood type can be valuable for, for example, future healthcare contacts, pregnancy or blood donation. The analysis gives you clear information about your blood type and your RhD status.
What is included in the blood group analysis?
The blood group analysis includes the following:
- ABO grouping: Shows whether your blood group is A, B, AB or O.
- RhD grouping: Shows whether you are RhD positive or RhD negative.
- Erythrocyte antibody screening: Examines whether there are irregular antibodies against red blood cells.
- Laboratory analysis: The analysis is only performed by the Karolinska University Laboratory.
What does the blood group analysis show?
The blood group analysis shows which of the four main ABO blood groups you belong to and whether you are RhD positive or RhD negative. The combination gives one of the eight most common blood group designations:
- A positive or A negative
- B positive or B negative
- AB positive or AB negative
- O positive or O negative
The analysis also shows whether the screening has shown signs of irregular erythrocyte antibodies. If the antibody screening is positive, additional analyses may be needed to identify which antibody(ies) are present.
What is a blood group?
A blood group describes which special markers, so-called antigens, are found on the surface of the red blood cells. There are many different blood group systems, but the ABO system and the Rh system are the most important in blood transfusions and pregnancy, among other things.
The ABO system determines whether the blood group is A, B, AB or O. The Rh system includes several different antigens, where the D antigen is used to indicate whether a person is RhD positive or RhD negative.
The ABO system – A, B, AB or O
The ABO system is divided into four main groups based on which antigens are found on the red blood cells and which antibodies are normally found in the blood plasma:
- Blood group A: Has A antigen on the red blood cells and normally anti-B in the plasma.
- Blood group B: Has B antigen on the red blood cells and normally anti-A in the plasma.
- Blood group AB: Has both A and B antigens and normally lacks anti-A and anti-B in the plasma.
- Blood group O: Lacks both A and B antigens and normally has both anti-A and anti-B in the plasma.
The ABO blood group is hereditary and does not normally change during life.
RhD system – positive or negative blood group
The RhD status shows whether the D antigen is present on the red blood cells:
- RhD positive: The D antigen is present on the red blood cells.
- RhD negative: The D antigen is absent on the red blood cells.
When the ABO group is combined with the RhD status, blood group designations such as A+, O− and AB+ are obtained. Approximately 85 percent of Sweden's population is RhD positive, while approximately 15 percent is RhD negative.
Why is blood grouping important?
Blood grouping is used to determine a person's blood group and is an important part of the safety of blood transfusions. If blood from incompatible blood groups is mixed, the immune system can react against the transfused red blood cells.
Therefore, in healthcare, up-to-date checks and compatibility tests are always carried out before a blood transfusion. A previous blood group result does not replace these safety checks.
Why is RhD status important during pregnancy?
RhD status is particularly important during pregnancy. If the pregnant woman is RhD negative and the fetus is RhD positive, the pregnant woman's immune system can in some cases form antibodies against the fetus's red blood cells. This is called RhD immunization.
In maternity care, there are established routines for detecting, preventing and following up on RhD immunization. A private blood group test does not replace blood grouping, antibody screening or other checks carried out during pregnancy.
What is erythrocyte antibody screening?
Erythrocyte antibody screening is an analysis that examines whether there are irregular antibodies directed against antigens on red blood cells. Such antibodies can be formed after a previous pregnancy or blood transfusion, among other things. They can be important to know because they can affect the choice of blood for a future transfusion and in some cases have significance during pregnancy.
A negative screening means that the analysis has not detected any irregular erythrocyte antibodies. A positive screening result means that antibodies may be present and that additional analysis and medical assessment may be needed.
Who can benefit from a blood group analysis?
A blood group analysis may be relevant for you if:
- Do not know your blood type.
- Want to know if you are RhD positive or RhD negative.
- Want information about your blood type for future healthcare contacts.
- Plan to become a blood donor and are curious about your blood type.
- Planning a pregnancy and want to know your RhD status.
- Previously been pregnant or received a blood transfusion and want to investigate whether irregular erythrocyte antibodies can be detected.
How common are the different blood types?
Blood type A is the most common in Sweden, followed by blood type O. Blood types B and AB are less common. A positive is the most common combination of ABO group and RhD status in Sweden. How common or uncommon a blood type is does not affect its medical significance. Healthcare needs access to blood from people with all blood types.
Can blood type change?
Blood type is hereditary and does not normally change during life. In very rare medical situations, for example after certain stem cell transplants, blood type relationships can change.
Does the analysis tell you who I can donate blood to?
The analysis shows your ABO and RhD blood type, but is not a complete assessment of who you can donate blood to or receive blood from. When donating blood and blood transfusion, additional checks are always carried out by the blood center or healthcare provider.
Blood type analysis of ABO, RhD and erythrocyte antibodies
The blood type test gives you information about your ABO blood type, your RhD status and whether there are signs of irregular erythrocyte antibodies. The analysis is performed by the Karolinska University Laboratory.
Normally, test results are provided within 5–7 working days.
