Hematology Case Study - Unmixed Sample

The sample (see PDF) is initially analyzed in manual mode with no mixing. The probe aspirates towards the bottom of the tube in the area containing concentrated RBCs:

RBC, HGB and HCT results are high on insufficiently or non-mixed samples (usually near the upper end of the analyzer’s reportable range or higher).
WBC and platelet results are low on non-mixed samples. WBCs and platelets are concentrated in the buffy coat region which is above where the probe aspirates.

After sufficient mixing and repeat testing, RBC, HGB and HCT results decrease while WBC and platelet results increase (compared to the initial run) because of the aspiration of a homogenous sample. With sufficient mixing, cell concentrations are consistent throughout the sample tube.

Indices generally remain similar between the initial and repeat runs because they are calculated ratios that are not affected by dilution or concentration of the sample.

Different samples may be affected by non-mixing in varying degrees because of how RBCs settle at different rates depending on the patient condition. Sysmex recommendation for mixing in manual mode:

Invert sample tube end to end at least 10 times.
Ensure all samples are adequately mixed, even freshly collected samples.
Micro-collection devices may require more vigorous mixing than a standard venous blood tube. Refer to the mixing instructions provided by the micro-collection device manufacturer.

The clinical applications or uses presented in these materials, including case studies, are provided for illustration purposes only. Prior to using any Sysmex device, please review the manufacturer’s instructions use. It is the healthcare provider’s responsibility to determine applicability in routine clinical practice.

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