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Background
Blood crossmatching is a key laboratory process used before a blood transfusion to ensure the compatibility of the donor’s and recipient’s blood. This procedure reduces the danger of potentially fatal hemolytic transfusion responses. The approach is founded on immunohematology concepts and a grasp of blood group systems, both of which are critical in evaluating transfusion compatibility. A mismatch in blood groups can cause serious transfusion responses, thus proper blood typing and crossmatching are critical for patient safety.
Blood crossmatching is a procedure that validates the compatibility of donor and recipient red blood cells (RBCs) while preventing immune-mediated cell death. It is based on antigen-antibody interactions, and recipient plasma may include alloantibodies that react with donor RBC antigens. The key concepts include ABO and Rh compatibility, antibody screening, direct and indirect antiglobulin assays, and crossmatch testing. ABO incompatibility can cause acute hemolytic transfusion responses. Antibody screening entails checking the recipient’s blood for unexpected alloantibodies that may react with donor RBCs, whereas crossmatch testing involves mixing donor RBCs with recipient serum to see agglutination or hemolysis, which indicates incompatibility.
Blood groups are classified according to the presence or absence of certain antigens on red blood cells (RBCs). The ABO system and the Rh system are the two most important blood group systems in transfusion medicine. The ABO system divides blood into four major categories based on the presence of A and B antigens on RBCs and associated antibodies in plasma. Mismatched transfusions can cause acute hemolytic transfusion responses (AHTR), resulting in RBC destruction, renal failure, and even death.
The Rh system, commonly known as the Rhesus system, is the second most critical for transfusion compatibility. It is predicated on the presence or lack of the D antigen on red blood cells. Rh-positive (Rh⁺) RBCs contain the D antigen, whereas Rh-negative (Rh⁻) do not. The Rh system is important in disorders such as hemolytic disease of newborns (HDN). An Rh-negative woman bearing a Rh-positive fetus may develop antibodies to fetal RBCs, resulting in hemolysis. Rh immunoglobulin injections are administered to avoid maternal sensitization.
There are three major types of crossmatching techniques: major crossmatch, minor crossmatch and electronic crossmatching. Major crossmatch involves testing the recipient’s serum against the donor’s RBCs indicating incompatibility and preventing blood transfusion. Minor crossmatch tests donor plasma against RBCs but is less common due to modern blood banking practices. Electronic crossmatching uses computerized algorithms and extensive blood bank records requiring a negative antibody screen and a reliable ABO group history for accurate results.
The limitation of the blood cross matching are like: It can not prevent the delayed transfusion hemolytic reaction with the transfusion of the compatible blood if there is an antibody titer which is not high to detect. It cannot detect the Rh compatibility; if there is a plasma from Rh– person cannot react with the Rh+ donor RBC in absence of the anti-D antibody. It cannot detect the minor ABO incompatibility. It cannot give the gurantee of the normal survival rate after the transfusion.
Indications/Applications
Pre-Transfusion Test for Anemia: Patients with severe or chronic conditions like iron deficiency anemia, aplastic anemia or bone marrow failure may require RBC transfusions. Hemolytic Anemia and acute blood loss require crossmatching to prevent transfusion reactions.
Surgical and perioperative management: Preoperative crossmatching may be required for major operations such as heart, orthopedic, and liver surgery. To obtain suitable blood for emergency procedures such as trauma or burst aneurysms, fast crossmatching is required.
RBC transfusions are frequently required for hematologic and oncologic disorders such as leukemia, lymphoma, and myelodysplastic syndrome. To avoid hemolytic responses in thalassemia and sickle cell disease, broad crossmatching is required.
Crossmatching and antibody screening are required for Rh incompatibility, as well as prenatal and neonatal transfusions.
Solid organ transplants require crossmatching to avoid rejection. Transfusions of red blood cells and platelets are required during hematopoietic stem cell transplantation (HSCT).
Autoimmune and Immune-Mediated Disorders: Autoimmune hemolytic anemia (AIHA) and paroxysmal nocturnal hemoglobinuria (PNH) may require RBC transfusions with special compatibility testing.
Special Conditions Requiring Blood Support: Emergency crossmatching is required in trauma, obstetric hemorrhage or sepsis. Exchange Transfusion is used in severe malaria, sickle cell crise and neonatal jaundice.
It prevents acute hemolytic transfusion reactions due to ABO and Rh incompatibility. It is used to reduce risk of delayed hemolytic transfusion reactions (DHTR) from minor antigen mismatches. It helps detect and avoid alloimmunization in patients receiving multiple transfusions. Preoperative and perioperative blood management uses blood crossmatching test. It is used in the management of pregnancy-related hematologic issues through screening for alloantibodies. It is used to make sure the organ transplantation and graft survival by preventing immune rejection. It is also used in the identification of rare blood types for special populations through donor registries.
Reference Range
Both minor and major cross-matches must indicate no agglutination of compatible recipient and donor blood. Blood which is incompatible in a substantial cross-match must not be transfused since the recipient’s large plasma volume carrying antibodies that can destroy the donor’s RBCs rapidly. Minor incompatibility is less harmful since that are present in the donor’s serum get diluted in recipient’s plasma and makes them ineffective.
Interpretation
A perfectly matched ABO and Rh result ensures safe transfusion of donor blood without risk of hemolytic reactions. Incorrect ABO matches like Type A receiving Type B blood, can lead to acute hemolytic transfusion reactions (AHTR) characterized by fever, chills, hypotension and kidney failure. Rh incompatibility, like Rh-negative receiving Rh-positive blood can cause alloimmunization especially dangerous for Rh-negative pregnant women as exposure to Rh-positive blood can cause hemolytic disease of the newborn in future pregnancies.
A negative antibody screen is ideal for transfusions preventing complications. A positive screen indicates the presence of alloantibodies suggesting exposure to foreign RBC antigens through a previous transfusion, pregnancy or organ transplant. A weakly positive screen indicates low levels of alloantibodies, potentially not clinically significant.
The Immediate Spin Crossmatch (ISXM) is a rapid test that detects ABO incompatibility by mixing donor and recipient plasma. A negative result confirms compatibility while a positive result indicates an ABO mismatch. Antiglobulin (AHG) crossmatch Interpretation detects non-ABO antibodies that could cause hemolysis. A negative result confirms donor blood is safe for transfusion while a positive result suggests clinically significant antibodies. Electronic crossmatch Interpretation uses computerized blood bank records to match donor and recipient blood. A successful electronic match allows transfusion to proceed safely without further serological testing. Failure in electronic crossmatching suggests errors in ABO typing or undetected antibodies, requiring manual testing.
Collection And Panels
Sample type: Whole blood
Sample collection method: Venipuncture
Sample collection container: Lavender top or EDTA tube, serum separator tube
Sample volume: 5 to 10 mL
Sample storage: Store the sample at 2 to 8°C.
Unacceptable samples: grossly hemolyzed or clotted samples are not acceptable.
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