Atypical nucleated RBCs (NRBCs) found on several patient blood smears between 2010 and 2012 were noted to resemble avian RBCs. NRBCs are not normally found in the circulation beyond the neonatal period and may indicate hematologic disease, malignancy in the bone marrow, or other severe conditions. Our blood smears with unusual NRBCs did not contain other abnormalities that typically accompany NRBCs, such as immature cells or dysplastic granulocytes. To investigate this anomaly, we considered possibilities such as contaminated collection tubes and instrument problems. The Retic-C Cell Control used with the LH 750 Hematology Analyzer contains a mixture of human and avian RBCs.
CBC count with differential tests were performed on blanks and routine laboratory samples run immediately after the Retic-C Cell Control on the LH 750 and LH 780 analyzers to recreate the conditions that might cause spillage into the next tube.
We experimentally reproduced the phenomenon of contamination of a subsequent tube with avian cells from a multiply punctured reticulocyte control tube.
We concluded that the NRBCs likely represented avian RBCs from the Retic-C Cell Control that had been introduced into the patient tubes.