Red cell antibody screen

What it measures

Tests patient plasma against reagent red cells of known phenotype to detect clinically significant antibodies other than anti-A and anti-B. Done before transfusion and in pregnancy.

Specimen and preparation

• Specimen: Plasma (EDTA); sample valid usually 72 h if transfused or pregnant in last 3 months
• Tube: Pink top
• Preparation: Record recent transfusions, pregnancies and medications (e.g. daratumumab interferes).

Reference range

Reference ranges differ between laboratories, methods and populations. Always use the range printed on your own lab report.

Causes of high values

• Alloantibodies after transfusion or pregnancy (e.g. anti-D, anti-K, anti-E, anti-Fya)
• Warm autoantibodies
• Passive anti-D after Rh immunoglobulin
• Anti-CD38 therapy interference

Method

Indirect antiglobulin technique with 2–3 screening cells by gel column, solid phase or tube

Good to know

A positive screen requires antibody identification with a larger panel and antigen-negative blood for transfusion.

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