1. What are instances when an accurate Rh type cannot be determined through routine testing?

- False reactions with Rh typing reagents cause inaccurate Rh type determination through routine testing. False positive reactions are likely caused by too heavy cell suspension, cold agglutinins, test incubated too long or drying, rouleaux formation, fibrin interference, contaminating low-incidence antibody in reagent, polyagglutination, bacterial contamination of reagent vial, incorrect selected reagent, too long centrifugation, and too high rpm applied during centrifugation. On the other hand, false negative reactions are likely caused by immunoglobulin-coated cells, Saline-suspended cells, failure to follow manufacturer’s directions precisely, omission of reagent manufacturer’s directions, too vigorous resuspension, incorrect selected reagent, variant antigen used, reagent deterioration, too short centrifugation, too low rpm applied during centrifugation.