Determination of Blood Groups | Practical By Dr.Sohaib

The determination of blood groups is primarily based on the ABO and Rh (Rhesus) blood group systems. This process relies on detecting specific antigens on the surface of red blood cells (RBCs) using known antibodies (antisera).Here is a comprehensive overview of how blood grouping works conceptually and how it is determined in a laboratory or practical setting:The ABO and Rh SystemsABO System: Your blood group depends on whether your RBCs have Antigen A, Antigen B, both, or neither.Rh System: Your blood is classified as "positive" ($+$) if the Rh antigen (D antigen) is present on your RBCs, and "negative" ($-$) if it is absent.Blood TypeAntigens on RBCsAntibodies in PlasmaAA antigenAnti-BBB antigenAnti-AABBoth A and B antigensNeitherONeitherBoth Anti-A and Anti-BPractical Determination: The Slide Agglutination TestIn a standard practical lab, blood typing is performed using the slide method. The key phenomenon observed is agglutination (clumping), which occurs when an antibody binds to its corresponding antigen.Equipment RequiredBlood sample (usually from a finger prick)Clean glass slidesAntisera kit: Anti-A (typically dyed blue), Anti-B (typically dyed yellow), and Anti-D (clear, for Rh factor)Sterile toothpicks or mixing sticksStep-by-Step ProcedurePreparation: Clean a glass slide and mark three separate zones or drops as A, B, and D (or Rh).Blood Placement: Place a fresh drop of blood onto each of the three marked areas.Adding Antisera:Add a drop of Anti-A serum to the first blood drop.Add a drop of Anti-B serum to the second blood drop.Add a drop of Anti-D serum to the third blood drop.Mixing: Use a separate clean toothpick for each drop to mix the blood and antisera thoroughly. Crucial: Using the same stick will cross-contaminate the results.Observation: Gently rock the slide for 1 to 2 minutes and observe for clumping (agglutination).