Serological Cross-Matching: Definition, Principle & Procedure

Instructor: Justine Fritzel

Justine has been a Registered Nurse for 10 years and has a Bachelor's of Science in Nursing degree.

Serological cross-matching is a vital step in ensuring a safe blood transfusion. In this lesson, we will learn what serological cross-matching is and how it is done.

A Day in the Hospital Laboratory

Shelley is a new lab tech starting her first day at the hospital lab. She is orienting with an experienced lab tech named Mike. Her day starts with a tour of the lab and equipment until they receive orders for blood for a transfusion. A twenty-year-old young man was in a motorcycle accident and is in the emergency room.

Blood transfusions involve donated blood being transfused to a patient with blood loss. People have different types of antigens in their blood which determines what type of blood they have- A, B, AB, or O. Antigens are proteins that trigger an immune reaction.

If a person receives incompatible blood, these antibodies will trigger an immune response and attack the transfused blood cells. This is called an immune-mediated hemolytic reaction that involves fever, low blood pressure, respiratory and kidney failure. It can be fatal.

It is essential that blood is tested for compatibility before transfusing.

What Is Serological Cross-Matching?

Serological cross-matching is testing of blood to ensure compatibility prior to transfusion. Serological refers to blood serum versus non-serological cross-matching which involves the use of advanced technology to test for compatibility of blood.

Mike explains to Shelley that they will go to the emergency room to draw blood on the patient. The blood that they collect will be used to determine his blood type.

Blood is drawn to determine blood type

Typically before cross-matching can be done, the patient's blood type has to be determined. This is through a blood test called type and screen. There are different steps to test the blood to determine which antigens are in the blood. This will determine the blood to be type A, B, AB, or O. Next a test is done to determine if another protein is present in the blood called Rhesus factor (Rh).

Mike tells Shelley that once the blood type is known, they can choose the correct type of donor blood to test for cross-matching. Type O blood doesn't have any antigens so it can be given to anyone regardless of blood type. A person with type AB blood can receive any type of blood- A, B, AB, or O. Type A and B can only receive their same type of blood or O.

They determine the injured man's blood type is A and Rh negative. Mike prepares to show Shelley the final step before the blood is ready for transfusion.

Process of Serological Cross-Matching

Since the patient has type A blood, Mike selects a donor blood unit that is also type A. He explains to Shelley that the last step prior to transfusion is cross-matching. Cross-matching involves testing the patient's blood and donor's blood for compatibility.

All of these steps are done to ensure the safest blood transfusion as possible. Knowing that incompatible blood can be fatal, it is essential to follow these steps.

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