A method of performing a nucleated red blood cell, nRBC, analysis with an automated hematology analyzer, the method comprising: (a) diluting a sample of whole blood with a reagent, wherein the reagent includes a red blood cell, RBC, lysing agent and a cell membrane permeable, nucleic acid binding fluorescent dye; (b) incubating the diluted blood sample of step (a) for an incubation period of less than 25 seconds, at a temperature ranging from 30°C to 50°C, thereby lysing red blood cells, RBC; (c) delivering the incubated sample from step (b) to a flow cell in the hematology analyzer; (d) exciting the incubated sample from step (c) with an excitation source as the incubated sample traverses the flow cell; (e) collecting a plurality of light scatter signals and a fluorescence emission signal from the excited sample; characterised in that (f) prior to performing an nRBC analysis, excluding nuclei-free particles and retaining nuclei-containing particles using a fluorescence trigger that is limited to fluorescence emission signals and is set to a fluorescence magnitude that is greater than fluorescence emission signals from RBCs, including RBC fragments, and is less than fluorescence emission signals from white blood cells, WBCs, and nRBCs; and (g) performing a nRBC analysis only on the nuclei-containing particles retained from the fluorescence trigger in step (f) wherein performing the nRBC analysis on only nuclei-containing particles comprises identifying, classifying, and counting nRBCs based on the light scattering and fluorescence emission signals collected in step (e) or based on the light scattering signals collected in step (e), wherein the nRBCs are distinguished in step (g) from white blood cells, WBCs, based on the plurality of light scatter signals alone or in combination with the magnitude of the fluorescence emission signal. (a) diluting a sample of whole blood with a reagent, wherein the reagent includes a red blood cell, RBC, lysing agent and a cell membrane permeable, nucleic acid binding fluorescent dye; (b) incubating the diluted blood sample of step (a) for an incubation period of less than 25 seconds, at a temperature ranging from 30°C to 50°C, thereby lysing red blood cells, RBC; (c) delivering the incubated sample from step (b) to a flow cell in the hematology analyzer; (d) exciting the incubated sample from step (c) with an excitation source as the incubated sample traverses the flow cell; (e) collecting a plurality of light scatter signals and a fluorescence emission signal from the excited sample; characterised in that (f) prior to performing an nRBC analysis, excluding nuclei-free particles and retaining nuclei-containing particles using a fluorescence trigger that is limited to fluorescence emission signals and is set to a fluorescence magnitude that is greater than fluorescence emission signals from RBCs, including RBC fragments, and is less than fluorescence emission signals from white blood cells, WBCs, and nRBCs; and (g) performing a nRBC analysis only on the nuclei-containing particles retained from the fluorescence trigger in step (f) wherein performing the nRBC analysis on only nuclei-containing particles comprises identifying, classifying, and counting nRBCs based on the light scattering and fluorescence emission signals collected in step (e) or based on the light scattering signals collected in step (e), wherein the nRBCs are distinguished in step (g) from white blood cells, WBCs, based on the plurality of light scatter signals alone or in combination with the magnitude of the fluorescence emission signal.