Hematology Question 21 Instructor

What are the major blood groups and how are they determined? What is involved in a “group and screen” and in a “cross-match” for blood? What blood group is universally transfusable?

Points for discussion:

  • Major blood groups: A, B, O representing the antigenic oligosaccharide chains anchored to glycoproteins on the RBC membrane. A and B antibodies in the serum result from “naturally occurring” isohemaglutinins produced in the absence of RBC exposure (i.e. The serum from a Group A red blood cell patient contains anti-B)
  • O negative blood = RBC has no immunogenic antigens on its surface to cause an ABO incompatible transfusion. Universal blood type (and should be given to all women of childbearing age in case of critical emergency where group and screen is not possible)
  • The Rh(D) blood group is included with the blood group due to its high rate of immunogenicity and implications with hemolytic disease of the newborn and hemolytic transfusion reactions
  • Group and Screen
      • Group = ABO and Rh group
      • Screen = detects any non-ABO alloantibodies in the serum acquired through prior transfusion or pregnancy
  • Cross Match
      • Assesses ABO compatibility between recipient plasma and donor red blood cells
Test Time
ABO + Rh 10 minutes
ABO + Rh + Ab screen (indirect antiglobulin test) 5 minutes
ABO + Rh + Ab screen + Cross Match 45 minutes (if IDAT is negative)

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