Blood typing is a test that determines a person’s blood type. The test is essential if you need a blood transfusion or are planning to donate blood. Not all blood types are compatible, so it’s important to know your blood group. Receiving blood that’s incompatible with your blood type could trigger a dangerous immune response.
A, B, AB, and O are the 4 major blood types. The types are based on small substances (molecules) on the surface of the blood cells.
When people who have one blood type receive blood from someone with a different blood type, it may cause their immune system to react. This is called ABO incompatibility.
Due to modern testing techniques, this problem is very rare.
If blood with antigens that you don’t have enters your system, your body will create antibodies against it. However, some people can still safely receive blood that isn’t their blood type. As long as the blood they receive doesn’t have any antigens that mark it as foreign, their bodies won’t attack it.
Blood typing is done prior to a blood transfusion or when classifying a person’s blood for donation. Blood typing is a fast and easy way to ensure that you receive the right kind of blood during surgery or after an injury. If you’re given incompatible blood, it can lead to blood clumping, or agglutination, which can be fatal.
Blood typing is especially important for pregnant women. If the mother is Rh-negative and the father is Rh-positive, the child will likely be Rh-positive. In these cases, the mother needs to receive a drug called RhoGAM. This drug will keep her body from forming antibodies that may attack the baby’s blood cells if their blood becomes mixed, which often happens during pregnancy.
How to Identify?
Your doctor will test samples of your blood for evidence of destruction of your red blood cells. They’ll also test your urine to see if it contains hemoglobin, a component released from broken-down blood cells. They’ll double-check your blood type and carry out the crossmatch procedure again.
While these procedures are performed, your doctor or nurse will monitor your vital signs, including your:
- blood pressure
- heart rate
If you have an ABO incompatibility reaction, you’ll have symptoms within a few minutes of receiving a transfusion. These may include:
- a strong feeling that something bad is about to happen
- fever and chills
- breathing difficulties
- muscle aches
- chest, abdominal, or back pain
- blood in your urine
What to Do?
The blood draw can be performed at a hospital or a clinical laboratory. Your skin will be cleaned before the test with an antiseptic to help prevent infection. A nurse or technician will wrap a band around your arm to make your veins more visible. They will use a needle to draw several samples of blood from your arm or hand. After the draw, gauze and a bandage will be placed over the puncture site.