How are nucleated RBCs (nRBCs) counted?

By William Aird

nRBCs are typically enumerated by one of the following methods:

  • Manual counting of Wright-Giemsa-stained peripheral smears:
    • Part of the traditional 100-cell manual differential leukocyte count.
    • Reported as number of nRBCs per 100 white blood cells (WBCs).
  • Automated hematology analyzers (for example, Sysmex)
    • Reported as relative number of nRBCs per 100 WBCs or as an absolute number.
Cool schematic of nucleated red cell from Sysmex.
Wright-Giemsa-stained peripheral blood smear showing nucleated red blood cell in center of field.
Counting nucleated red cells in an automated cell counter. In the WNR Channel, the analyzer measures side fluorescence and forward scatter. Side fluorescence measures the nucleic acid content to identify NRBCs in the same channel in which white cells are counted. Forward scatter measures cell size. WNR, white count and nucleated red blood cells. Source.