Cross Match Principle, Procedure, Result.


Cross Match

  • Cross Match is a laboratory test, performed prior to a blood transfusion to determine whether donor blood is compatible (or incompatible) with recipient blood.
  • The Compatibility can be determined by matching the different blood group systems, such as ABO and Rh system, and/or by directly testing for the presence of antibodies against a sample of donor tissues or blood.
  • The main purpose of this test is to distinguish the appearance of antibodies in the recipient against the red blood cells of the donor. These antibodies can be found on the surface of red blood cells of the donor after transfusion. 
  • An incompatible transfusion can lead to severe hemolytic anemia and even death.
  • The Cross Match test does not perform in dogs and horses, because in them the naturally occurring antibody against important hemolytic red blood cell antigens are absent. Hence, these animals need sensitization to the red cell antigen, before a hemolytic reaction will occur.  
  • After completion of blood transfusion to a dog or horse, a crossmatch should be performed prior to any subsequent transfusions to detect antibodies that may have been produced against a different red blood cell antigen.

Types of cross match

There are present three types of  cross match test such as;

  1. Major crossmatch: It is considered the most important one. This method is used to confirm the production of antibodies in the recipient against transfused red blood cell antigens (from the donor). Hence, we required RBC from the donor and serum from the recipient.
  2. Minor crossmatch: This method is used to detects the presence of antibodies within the donor serum to the recipient’s red blood cells. Hence, for this test, we required RBC from the recipient and serum from the donor.
  3. Autocontrol: This cross match test is performed between the recipient serum with recipient red blood cells.

Objective

This test is performed as the final step of pretransfusion compatibility testing. The main purpose of compatibility tests are to detect: irregular antibodies; errors in ABO grouping, and clerical errors in patient identification and result recording. The cross match is used to detect;

  • Most recipient antibodies directed against the donor’s red blood cell antigens.
  • Most donor antibodies directed against recipient’s red blood cell antigens.
  • Major errors in ABO grouping, labeling, and identification of donors and recipients.

Principle of Cross Match

Cross matching is a serological detection of any clinically significant irregular/unexpected antibodies in either donor or recipient’s blood. There are involve two distinct method of cross matches such as Major Cross Match and Minor Cross Match.

In Major Cross Match the donor’s red cells are tested with the recipient’s serum to find out the appearance of any antibody which may lead to the hemolysis or agglutination of donor red cells. This method is more important than the minor cross match. While in Minor Cross Match, the donor’s plasma tested with the recipient’s red cells to find out the appearance of an antibody which may lead to the hemolysis or agglutination of the recipient’s red cells.

During the Major Cross Match, the Red Cells are taken from the Donor’s body while Serum/Plasma taken from the Recipient’s body. In Minor Cross Match, the Serum/Plasma is taken from the Donor’s body while Red Cells are taken from the Recipient’s body.

Requirement

  • Red Cells from donor’s body and Serum/Plasma from Recipient’s (For Major Cross Match).
  • Serum/Plasma from donor’s body and Red Cells from Recipient’s (For Minor Cross Match).

Cross Matching Procedure

There are present various techniques for cross-matching. Among them, Anti-human globulin (AHG) cross match technique is widely used. Some examples of Cross Match techniques are;

  • Saline Cross Match; used to detect IgM antibody.
  • Albumin Cross Match; used to detect IgG antibody.
  • Anti-Human Globulin (AHG) Cross Match; used to detect IgG antibody.

Major Cross Match

  1. Collect and prepare the Red Cells from donor’s body and Serum/Plasma from Recipient’s body.
  2. Prepare 3-5% saline cell suspension of red cells.
  3. Take a clean test tube and label it.
  4. Add 2 drops of recipient’s serum and 1 drop of donor cell suspension within the test tube.
  5. Mix them well.
  6. Incubate the test tube at 37 degrees Celsius for about 60 minutes.
  7. Empty the serum completely and rinse the cells three times in saline.
  8. Add 2 drops of Anti-human Globulin (AHG) and mix well.
  9. Centrifuge the sample at 1500 rpm for 1 minute.
  10. Now, observe the sample microscopically for agglutination.
  11. If macroscopic agglutination is not seen, shift a small amount onto a glass slide and examine for microscopic agglutination. Rouleaux is not an indication of incompatibility.
Major Cross Match
Major Cross Match | Image modified from http://laboratorytests.org/wp-content/uploads/2019/07/Major-Cross-Matching.jpg

Minor Cross Match

  1. Collect and prepare the Serum/Plasma from donor’s body and Red Cells from Recipient’s body.
  2. Take a clean test tube and label it.
  3. Add 2 drops of donor’s serum and 1 drop of recipient’s cell suspension within the test tube.
  4. Mix them well.
  5. Incubate the test tube at 37 degrees Celsius for about 60 minutes.
  6. Decant the serum completely.
  7. Wash the cells three times in saline.
  8. Add two drops of Anti-human Globulin (AHG) and mix.
  9. Allow to stand at room temperature for 5 minutes.
  10. Centrifuge the sample at 1500 rpm for 1 minute.
  11. Now, observe the sample microscopically for agglutination.
    1. If macroscopic agglutination is not seen, shift a small amount onto a glass slide and examine for microscopic agglutination. Rouleaux is not an indication of incompatibility.

Result 

  • Positive Result: Agglutination will not occur if the blood sample of donor and recipient is Compatible in both major and minor crossmatch.
  • Negative Result: Agglutination will occur if the blood sample of donor and recipient is incompatible in both major and minor crossmatch.

If any blood sample shows incompatibility during the major cross match, then the blood sample should never be transfused, because the large plasma volume of the recipient blood containing antibodies can destroy the donor’s red cells easily. The minor incompatibility is less important because the donor’s serum which contains the antibodies is diluted in the recipient’s own plasma, making the antibodies very dilute and ineffective.

Application of Cross Match test

  • This test is used during a blood transfusion.
  • Cross Match test is used if anyone having a certain medical problem that could cause significant blood loss, such as a cesarean section, a renal biopsy, or a cholecystectomy.
  • Used for sickle cell disease or thalassemia.
  • Used to check the effects of chemotherapy.
  • Used for detection of a bleeding disorder, for example, hemophilia.
  • During pregnancy, this test is used to find out if the patient is Rh-negative or positive.
  • This test is performed during organ transplant, bone marrow transplant, or tissue transplant.