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SOP

Unexpected Antibody Screening

SOP for detecting clinically significant alloantibodies in patient serum using reagent screening cells.

Last verified 1 month ago 1 min read Blood Bank / Transfusion Medicine Immunohematology #blood bank #immunohematology #antibody screen #alloantibody
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Document Control
Version
1.0
Effective
Aug 28, 2026
Reviewed
Aug 29, 2026
Department
Blood Bank / Transfusion Medicine
Principle

Group O screening cells lack A and B antigens, preventing interference from ABO antibodies. They are selected to express a wide variety of clinically significant antigens to maximize the chance of detecting alloantibodies.

Standard Operating Procedure: Antibody Screening

1. Purpose: Detect unexpected RBC alloantibodies prior to transfusion or during pregnancy.

2. Specimen: Patient serum or plasma.

3. Reagents: 2-3 vials of Group O screening cells (containing homozygous expression of common antigens), LISS/PEG, AHG, check cells.

4. Procedure:

  • Add 2 drops patient serum to separate tubes containing 1 drop of Screening Cell I, II, (and III).
  • Incubate at 37°C for 15-30 mins.
  • Wash 3-4 times with saline.
  • Add AHG, centrifuge, read. Add check cells to negatives.

5. Interpretation: Agglutination = Positive screen (requires antibody identification panel). No agglutination = Negative screen.

Frequently Asked Questions

To prevent naturally occurring anti-A or anti-B in the patient's serum from causing a false-positive agglutination.