Standard Operating Procedure: Major Crossmatching

1. Purpose: Ensure donor RBCs are compatible with patient serum to prevent hemolytic transfusion reactions.

2. Specimen: Patient serum/plasma (drawn within 3 days if previously transfused/pregnant), donor pilot tube.

3. Reagents: Saline, LISS/PEG, 37°C incubator, AHG, check cells.

4. Procedure (Serologic Crossmatch):

• Mix 2 drops patient serum with 1 drop donor 3-5% RBC suspension.
• Immediate Spin (IS): Centrifuge, read for ABO incompatibility.
• 37°C Phase: Add enhancement, incubate 15-30 mins at 37°C, centrifuge, read.
• AHG Phase: Wash 3-4 times, add AHG, centrifuge, read. Add check cells to negative results.

5. Interpretation: No hemolysis or agglutination at any phase = Compatible. Any agglutination/hemolysis = Incompatible.