Patient tested was new to the hospital. The sample received was tested for ABO RH using automated gel methodology. The patient typed RH negative using automated machine. Patient sample was tested again using manual tube method. The sample tested RH Positive using manual tube method. Patient history was evaluated. Patient had recently received to RH negative units. Futher investigation determined that the patient is RH positive using manual method of testing.
Red blood cells are pipetted from the very top of sample when the technologist is manual centrifuge testing. The automated machine pipettes the red cells from the very bottom of the test tube. The different pipetting locations of the automated machine and technologist was determined to be the cause of typing discrepancies. The automated pipette goes to lower portion of the test tube where the newer donated RH negative red cells are. The technologist pipetted the sample from the top of the red cells where older patient red cells are located.
In summary technologist should determine patient blood type history and testing methodologies when investigating typing discrepancies in order to prevent blood transfusion reactions.