Sysmex XE-2100
Counting of Red Cells and Platelets
by impedance & fluorescent techniques
Methods employed


Red cells are measured by impedence only
Platelets are measured in two channels
–
–


Impedance Channel (default)
Fluorescent Channel
Impedance Channel is default count
In instances of abnormality when the
algorithm will come into play
Impedance Channel - Overview




Red cells and platelets
Hydrodynamic Focusing of cells to be
counted
DC aperture Impedance
Excellent Linearity
–
with limitations
Impedance Counting

Platelet count is fine when
histograms are well defined

But in case of abnormality,
platelet count suffers from
Rbc interference
PLT_DC
RBC_DC
Optical PLT Count
RET(Plt-O)

In those instances Fluorescent Optical
Platelet count would be
preferable for several
reasons
Optical System



Higher sensitivity due staining
of cells
Better Rbc/plt resolution
Necessary in
–
–
–
Small (Microcytic) RBC
Giant Platelets
Rbc Fragments
Measurements used in Optical System




Forward Scatter - size of cells
Side Scatter - internal structure (i.e size of nucleus)
Fluorescence - Measurement of RNA/DNA stained
Fluorescent Optical Platelet count is performed with
reticulocyte count
Accurate Platelet Counting
In the presence of Rbc fragments,
microcytic RBC or giant platelets,
the PLT distribution curve is
clearly affected
However in the RET scattergram,
the RBC and PLT-O clusters are
obviously distinct
Limitations of Optical Platelet Counts

WBC fragments are included in the
Optical Platelet Count

Generates a “Plt Abn Scattergram” flag
PLT Switching Algorithm
RBC fragments/ small Rbcs:
PLT-I

PLT-O
WBC fragments / giant platelets:
PLT-I

PLT-O
PLT Switching Algorithm
No
PLT-I, Low reliability
Yes
PLT-O, Low reliability
Yes
PLT Vote out
PLT-I is reported
No
PLT-O is reported
Changing the count?



PLT Abn Distribution flag
or
Fragments? flag is detected from RBC
channel
or
PLT-I/PLT-O count differences
+/- 15%
The PLT-I/O Switching Rule

For low-PLT#
– PLT-O# may more reliable than PLT-I#, when PLT-I# are
low

Customizable switching trigger for PLT-I#
– Default setting is 50.0x10^3/uL
Adding PLT-I/O switching rule