False-Positive Reactions With Rh Typing Reagents

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The page below is a sample from the LabCE course Overview Of Major Antigens of the Rh Blood Group System (retired 2/12/2020). Access the complete course and earn ASCLS P.A.C.E.-approved continuing education credits by subscribing online.

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False-Positive Reactions With Rh Typing Reagents

Rh antigen testing must be done with strict adherence to manufacturer's instructions and a clear understanding of the limitations of the reagents used in the procedure. The table below delineates some of the more commonly seen false-positive reactions with Rh typing reagents and provides insight into the causes and corrective actions that may be undertaken when these problems are presented.
Likely CauseCorrective action, in compliance with direction circular
Fibrin interferenceUse saline-washed cells; retest
Rouleaux Use saline-washed cells; retest
Bacterial contamination of reagent vial Open new vial of reagent; retest
Incorrect reagent selected Read vial label carefully when repeating test
Centrifugation too long Repeat test using shorter centrifugation time, per package insert/SOP
Modified from Harmening, D: Table 7-10, Modern blood banking and transfusion practices, 6thed, FA Davis, Philadelphia, PA, 2012, p 162.
Fung, MK, Eder, AF, Spitalnik, SL, Westhoff, CM (eds): Technical Manual, 19th ed. AABB, Bethesda, MD, 2017, p 313.