With the ADVIA hematology analyzer, red blood cells (RBC) are flowed individually through a laser light in a flow cell. As the RBC passes through the light, it scatters the laser light in a forward (low angle) direction and in a side (high angle) direction. The degree of forward scatter is measured as the cell volume, as depicted here (larger cells scattering more light than smaller cells), whereas the degree of side scatter is equivalent to the cellular hemoglobin content (CH) in pg (cells with less hemoglobin would scatter less light in the side direction). The ADVIA then compiles the individual RBC hemoglobin content results as a histogram (RBC CH), where the number of cells is shown on the Y-axis and the hemoglobin content or cellular hemoglobin (CH) is shown on the X-axis (pg), ranging from 0-100 pg. The CH result provided by the analyzer is the mean cellular hemoglobin content. Unlike the CHCM, this measurement does not take into account volume and is only content, not concentration per unit volume.
